Microbiology > Ch. 16 > Flashcards

Ch. 16 Flashcards

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1
Q

What does familial tendency for allergy indicate?

A
  • Parent allergic to pollen → child may be allergic to cat dander
  • Risk increases: 25% if one parent is atopic
  • 50%+ if multiple family members affected

Linked to IgE production, mast cell sensitivity, tissue reactivity.

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2
Q

What are the two main phases of an allergic reaction?

A
  • Sensitization Phase
  • Provocation Phase

Sensitization involves initial exposure to allergen, while provocation involves subsequent exposure leading to symptoms.

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3
Q

What occurs during the Sensitization Phase of an allergic reaction?

A
  • Initial exposure to allergen
  • Activation of B cells → production of IgE
  • IgE binds to mast cells and basophils
  • Body is now ‘primed’ for future response

No symptoms occur during this phase.

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4
Q

What happens during the Provocation Phase of an allergic reaction?

A
  • Allergen binds to IgE on mast cells
  • Triggers release of chemical mediators
  • Results in visible allergic symptoms (sneezing, itching, swelling, etc.)

This phase follows the sensitization phase.

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5
Q

What is the mechanism of Type 1 Hypersensitivity?

A
  • Primary contact/Sensitization
  • Antigen processed by dendritic cells activates T in H lymph nodes
  • Interaction between T and B cells produces plasma H cells that produce IgE

IgE attaches to mast cells and basophils, priming the immune system.

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6
Q

What makes IgE unique?

A
  • IgE’s Fc region binds tightly to:
    • Mast cells
    • Basophils

Sensitized mast cells and basophils are now ‘armed’ and ready to react upon re-exposure.

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7
Q

What is the result of degranulation in an allergic response?

A
  • Releases mediators with physiological effects such as:
    • Vasodilation
    • Bronchoconstriction

Degranulation occurs when allergen binds to the IgE-mast cell complex.

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8
Q

What are the chemical mediators released by mast cells and basophils?

A
  • Histamine
  • Serotonin
  • Leukotrienes
  • Prostaglandins
  • Bradykinin

These mediators account for the scope of allergic symptoms.

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9
Q

What are common responses to chemical mediators in allergic reactions?

A
  • Rashes
  • Itching
  • Redness
  • Rhinitis
  • Sneezing
  • Diarrhea
  • Tears

General targets include skin, upper respiratory tract, GI tract, and conjunctiva.

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10
Q

What are examples of Type 1 Hypersensitivity diseases?

A
  • Hay fever
  • Allergic asthma
  • Atopic dermatitis (Eczema)
  • Food allergy
  • Drug allergy

These conditions can lead to symptoms ranging from mild to severe, including anaphylaxis.

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11
Q

Define immunopathology.

A

The study of disease states associated with underreactivity and overreactivity of the immune response

Includes conditions like allergy, hypersensitivity, autoimmunity, and immunodeficiency.

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12
Q

What is anaphylaxis?

A
  • A reaction to foreign protein
  • Acute symptoms: itching, sneezing, difficult breathing, prostration, convulsions, death

Two types in humans: cutaneous and systemic anaphylaxis.

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13
Q

What are the types of allergy tests?

A
  • In Vitro (Lab-Based) Tests
  • In Vivo (Skin-Based) Tests

In vitro tests include tryptase levels and IgE assays; in vivo tests involve direct exposure to allergens.

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14
Q

What is the purpose of skin testing in allergy diagnosis?

A
  • Detects atopic and anaphylactic sensitivities
  • Confirms IgE-mediated allergic responses

Allergen extracts are injected or scratched onto the skin to monitor reactions.

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15
Q

List the treatment and prevention strategies for allergies.

A
  • Allergen avoidance
  • Drug therapies (Antihistamines, Corticosteroids)
  • Desensitization (Allergen Immunotherapy)
  • Prevention strategies

Aims to reduce IgE response and manage symptoms.

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16
Q

What are common symptom-relieving drugs for allergies?

A
  • Antihistamines
  • Aspirin/Acetaminophen
  • Theophylline
  • Epinephrine

These medications help relieve symptoms and manage allergic reactions.

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17
Q

How do allergy shots (desensitization therapy) work?

A
  • IgG acts as a ‘decoy shield’
  • Blocks allergens from reaching IgE-coated mast cells

Allergen injections cause massive production of allergen-specific IgG antibodies.

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18
Q

What is the role of IgG in allergic reactions?

A

Acts like a ‘decoy shield’ blocking allergens from reaching IgE-coated mast cells

An allergen injection causes massive amounts of allergen-specific IgG antibodies to be produced.

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19
Q

Type II Hypersensitivity involves which antibodies?

A
  • IgG
  • IgM

These antibodies bind to cell surface antigens, triggering complement activation and cell lysis.

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20
Q

What are alloantigens?

A

Surface molecules that vary between individuals of the same species

They are significant in transfusion reactions.

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21
Q

What triggers transfusion reactions?

A

Donated RBCs react with recipient antibodies

This leads to complement cascade activation and massive hemolysis.

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22
Q

What are the common symptoms of hemolysis?

A
  • Fever
  • Anemia
  • Jaundice

These symptoms can occur due to transfusion reactions.

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23
Q

What is the purpose of RhoGAM injection during pregnancy?

A

Contains anti-Rh antibodies to prevent sensitization

Given at 28-32 weeks and 2 days after birth.

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24
Q

What is the Arthus Reaction?

A

Acute localized inflammation following a booster vaccine or repeated drug injection

Symptoms include redness, heat, swelling, and intense pain.

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25
Type IV Hypersensitivity is mediated by which cells?
* T cells (especially CD4⁺ and CD8⁺) ## Footnote Symptoms appear 24-72 hours after re-exposure.
26
What is the **tuberculin skin test** used for?
To reveal if a patient is positive or negative for Mycobacterium tuberculosis ## Footnote Induration is measured after 48-72 hours.
27
What triggers **contact dermatitis**?
Resins (poison ivy/oak), haptens (nickel, cosmetics, latex) ## Footnote Allergen penetrates skin and is processed by Langerhans cells.
28
What are the **portals of entry** for allergens?
* Inhalants * Ingestants * Injectants * Contactants ## Footnote Each type enters the body through different routes.
29
What happens during **graft rejection**?
T lymphocytes recognize donor tissue as 'non-self' ## Footnote Cytotoxic T cells and NK cells attack grafted cells.
30
What is the primary reason for **graft rejection** in organ transplantation?
* T lymphocytes recognize donor tissue as 'non-self' * Cytotoxic T cells (CD8⁺) and NK cells attack grafted cells * Results in graft rejection and tissue destruction ## Footnote Understanding the immune response is crucial for successful organ transplantation.
31
What are the two mechanisms of **graft rejection**?
* Direct recognition: Host T cells recognize foreign MHC markers on donor cells * Indirect recognition: Host APCs process donor antigens and present to helper T cells ## Footnote These mechanisms explain how the immune system identifies and attacks foreign tissues.
32
Name the techniques for **testing compatibility** in organ transplantation.
* Blood type matching (ABO, Rh) * HLA/MHC matching to reduce T cell activation * Mixed lymphocyte reaction (MLR) assesses donor-recipient reactivity ## Footnote Compatibility testing is essential to minimize the risk of rejection.
33
What are the **classes of grafts** based on MHC similarity?
* Autograft: recipient also serves as donor * Isograft: tissue from identical twin * Allograft: genetically different individuals of the same species * Xenograft: individuals of different species ## Footnote Understanding graft classes helps in selecting appropriate donors.
34
What is the purpose of **tissue matching techniques**?
* Mixed Lymphocyte Reaction (MLR): checks for T-cell activation/proliferation * Tissue Typing (HLA typing): detects HLA antigens on lymphocytes * ABO Blood Typing: ensures compatibility in organ transplants ## Footnote These techniques help in avoiding graft incompatibility.
35
What are common **sources of transplants**?
* Live donors: kidney, liver, marrow * Cadavers: heart, cornea * Fetal tissue: experimental uses (e.g., Parkinson’s) ## Footnote Various sources are utilized to meet the demand for organ transplants.
36
What conditions are treated with **hematopoietic stem cell transplantation**?
* Immune deficiencies * Leukemia & cancers * Aplastic anemia * Radiation damage ## Footnote This type of transplantation is crucial for restoring blood cell production.
37
Define **autoimmunity**.
Immune system mounts a response against self-antigens ## Footnote Autoimmunity can lead to various autoimmune diseases affecting different organs.
38
What are the **types of autoimmune diseases**?
* Systemic: affect multiple organs (e.g., Systemic lupus erythematosus) * Organ-specific: target one tissue or organ (e.g., Type 1 diabetes, Hashimoto’s thyroiditis) ## Footnote Understanding the classification helps in diagnosis and treatment.
39
What are the **mechanisms of damage** in autoimmune diseases?
* Type II (Cytotoxic) hypersensitivity * Type III (Immune Complex) hypersensitivity ## Footnote These mechanisms explain how autoantibodies trigger injury to tissues.
40
What are the **key contributing factors** influencing autoimmunity?
* Genetics * Gender * Environmental exposure ## Footnote These factors can increase susceptibility to autoimmune diseases.
41
True or false: **Women are more affected by autoimmune diseases** than men, especially during childbearing years.
TRUE ## Footnote Hormonal changes and pregnancy-related immune shifts may influence this disparity.
42
What is the **Sequestered Antigen Theory**?
Hidden tissues become exposed and mistaken for foreign ## Footnote This theory explains one potential origin of autoimmune diseases.
43
What is **molecular mimicry** in the context of autoimmune diseases?
Microbial antigens mimic self, leading to self-tissue attack ## Footnote Examples include rheumatic fever and type 1 diabetes.
44
What is the result of **Type 1 diabetes** in autoimmune disease?
* Autoimmunity targets the pancreas * Autoantibodies and sensitized T cells destroy pancreatic islets * Leads to insulin dependence ## Footnote Understanding the mechanism is crucial for managing diabetes.
45
What are the **types of hypersensitivity reactions** according to Gell & Coombs classification?
* Type I: Immediate (e.g., hay fever, anaphylaxis) * Type II: Antibody-mediated cell damage (IgG, IgM) * Type III: Immune complex-mediated reactions * Type IV: Delayed, T-cell mediated (e.g., contact dermatitis) ## Footnote This classification helps in understanding allergic reactions and their management.
46
What are common **sources of allergens**?
* Industrial & household chemicals * Cosmetics, food, drugs * Animal dander, pollen, mold spores, dust mites ## Footnote Identifying allergens is essential for managing allergic reactions.
47
What are the **two levels of severity** in Type I hypersensitivity?
* Atopy: localized, chronic allergy (e.g., hay fever, eczema) * Anaphylaxis: systemic, severe allergic reaction ## Footnote Understanding these levels is important for treatment and emergency response.
48
What does the term **allergy** refer to?
A condition of altered reactivity or exaggerated immune responsiveness manifested by inflammatory symptoms ## Footnote Allergy is sometimes used interchangeably with hypersensitivity, but some experts differentiate between immediate reactions and other forms of overreactions.
49
What are **allergens**?
Antigens that cause allergic reactions in sensitive individuals ## Footnote Allergic and hypersensitive individuals are acutely sensitive to repeated contact with allergens.
50
What types of immune reactions are involved in allergies and hypersensitivities?
* Humoral actions * Cell-mediated actions * Inflammatory response * Phagocytosis * Complement ## Footnote These reactions are the same types involved in protective immunities.
51
Originally, allergies and hypersensitivities were defined as either **immediate** or _______.
delayed ## Footnote This classification was based on the time lapse between contact with the allergen and the onset of symptoms.
52
Type I hypersensitivity is characterized by **B-cell-mediated** and _______ reactions.
antibody-mediated ## Footnote Examples include hay fever and anaphylaxis.
53
Type II hypersensitivity involves **antibody-mediated** reactions related to _______.
blood type incompatibilities ## Footnote This type of hypersensitivity can lead to serious immune responses.
54
Type III hypersensitivity is associated with **immune complex** diseases such as _______.
* rheumatoid arthritis * serum sickness ## Footnote These conditions arise from the accumulation of immune complexes in tissues.
55
Type IV hypersensitivity is characterized by **T-cell-mediated** reactions, including _______.
* contact dermatitis * graft rejection ## Footnote This type involves delayed reactions and is distinct from antibody-mediated responses.
56
What can a lack of **T cell surveillance** lead to?
Cancer cell survival ## Footnote This highlights the importance of T cells in monitoring and eliminating cancerous cells.
57
A loss or lack of **T cells**, **B cells**, or both compromises the _______.
immune system ## Footnote This can lead to immunodeficiency, making individuals more susceptible to infections.
58
What are the **four major categories** of immune system pathologies involving overreactions to antigens?
* Type I: Common allergy and anaphylaxis * Type II: IgG- and IgM-mediated cell damage * Type III: Immune complex diseases * Type IV: Delayed hypersensitivity ## Footnote This classification was introduced by immunologists P. Gell and R. Coombs.
59
Type I allergies are associated with which **immunoglobulin**?
IgE ## Footnote IgE-mediated reactions involve mast cells, basophils, and allergic mediators.
60
What is the difference between **atopy** and **anaphylaxis**?
* Atopy: Chronic allergy, localized effects, not life-threatening * Anaphylaxis: Systemic, potentially fatal reaction, involves airway obstruction and circulatory collapse ## Footnote Atopy includes conditions like hay fever or eczema.
61
What types of **reactions** are involved in Type II immunopathologies?
IgG and IgM antibodies act upon cells with complement, causing cell lysis ## Footnote This includes some autoimmune diseases.
62
What are the **physiological effects** of allergies that cause major symptoms?
* Redness * Heat * Skin eruptions * Edema * Granuloma ## Footnote These symptoms are caused by some of the same chemical mediators involved in inflammation.
63
What is the **predisposition** for atopic allergies?
Strong familial association ## Footnote Generalized susceptibility is hereditary, not allergy to a specific substance.
64
True or false: Allergies and hypersensitivities are often mistaken for **infections**.
TRUE ## Footnote Both involve tissue damage and trigger the inflammatory response.
65
What percentage of the population is estimated to be prone to **atopic allergy**?
10% to 30% ## Footnote This estimate may be low due to self-treatment with over-the-counter medicines.
66
What is the **economic impact** of allergies on society?
Significant monetary loss due to medical treatment and employee absenteeism ## Footnote The 40 million people afflicted with hay fever spend about half a billion dollars annually.
67
Fill in the blank: The antigens that elicit reactions in immunopathologies can be **________** or endogenous.
exogenous ## Footnote Exogenous antigens originate from outside the body, while endogenous arise from self tissue.
68
What are the **mechanisms** involved in immediate allergies?
* IgE * Mast cells * Sensitization * Provocation ## Footnote These mechanisms are crucial for understanding the process of allergic reactions.
69
What is the **basis for atopy**?
* Inheritance of genes favoring IgE production * Increased reactivity of mast cells * Increased susceptibility of target tissue to allergic mediators ## Footnote Allergic persons often exhibit a combination of syndromes such as hay fever, eczema, and asthma.
70
What factors affect the **onset of allergy**?
* Age * Infection * Geographic locale ## Footnote New allergies can develop throughout an allergic person's life, especially with new exposures.
71
True or false: Allergic reactions can **last a lifetime** for some individuals.
TRUE ## Footnote Others may outgrow allergies or develop them later in life.
72
What are the **immunogenic characteristics** of allergens?
* Proteins are more allergenic than carbohydrates, fats, or nucleic acids * Some allergens are haptens ## Footnote Haptens are nonproteinaceous substances that can form complexes with carrier molecules in the body.
73
List the **common allergens** classified by portal of entry.
* Inhalants: pollen, dust, mold spores, dander, animal hair, insect parts * Injectants: food, oral drugs, hymenopteran venom, vaccines, serum * Contactants: topical drugs, cosmetics, heavy metals, detergents ## Footnote Allergens typically enter through the respiratory tract, gastrointestinal tract, and skin.
74
What are **inhalants**?
* Airborne environmental allergens like pollen, house dust, dander, and fungal spores ## Footnote Each geographic region has a unique combination of airborne substances that varies with season and humidity.
75
What is the most common **airborne allergen**?
Pollen ## Footnote Pollen is released seasonally by reproductive structures of pines and flowering plants.
76
What is **house dust** primarily composed of?
* Organic debris * Soil * Human skin cells * Bacteria and fungi * Decomposed skeletons of tiny mites ## Footnote The component that accounts for most dust allergies is the decomposed skeletons of mites.
77
What are **ingestants** in the context of allergies?
Allergens that enter by mouth, often causing food allergies ## Footnote Common food allergens include milk, peanuts, wheat, shellfish, and eggs.
78
What are **injectant allergies**?
Adverse reactions to injected drugs or substances ## Footnote A natural source of injectants is venom from stings by hymenopterans.
79
What are **contactants**?
Allergens that enter through the skin ## Footnote Many contact allergies are of the type IV, delayed variety.
80
What causes **sensitization** in allergic individuals?
The immune system's response to allergens that does not occur in non-allergic individuals ## Footnote This process leads to symptoms like sneezing and wheezing in response to allergens.
81
What percentage of the world's population is affected by **allergies**?
Over 40% ## Footnote This statistic highlights the widespread nature of allergies globally.
82
What is the initial encounter with an allergen that primes the immune system called?
Sensitizing dose ## Footnote This dose generally elicits no signs or symptoms but prepares the immune system for future encounters.
83
What type of cells are produced during the initial encounter with an allergen that are ready to react upon subsequent exposure?
Memory cells and immunoglobulin ## Footnote These components are crucial for the immune response to allergens.
84
True or false: It is generally believed that individuals can show an allergy upon first contact with an allergen.
FALSE ## Footnote It is believed that these individuals unknowingly had prior contact with the allergen.
85
What is a possible source of 'hidden' allergens that can lead to allergies?
Foods ## Footnote Foods can contain allergens that may not be immediately recognized.
86
What is the antibody associated with allergies called?
Immunoglobulin E (IgE) ## Footnote IgE has a unique Fc region that binds to mast cells and basophils.
87
What are the two main types of cells involved in IgE-mediated allergies?
* Mast cells * Basophils ## Footnote Both cell types play critical roles in the allergic response.
88
Where are **mast cells** predominantly located in the body?
* Lungs * Skin * Gastrointestinal tract * Genitourinary tract ## Footnote Mast cells are found in high concentrations in these tissues.
89
What is the role of **basophils** in the context of allergies?
Circulate in blood and migrate into tissues ## Footnote Basophils are important for the allergic response due to their mobility.
90
What do mast cells and basophils release when triggered by a specific allergen?
Contents of their granules ## Footnote This process is known as degranulation and is crucial for the allergic reaction.
91
What is the first step in the **sensitization** process of allergic reactions?
Allergens enter through mucous membranes and are picked up by a dendritic cell ## Footnote This initial contact with the allergen is crucial for the subsequent immune response.
92
During **subsequent exposure** to an allergen, what happens to the **IgE-primed mast cells**?
Allergen attaches to IgE on mast cells, triggering degranulation and release of allergic mediators ## Footnote Mast cells can remain in tissues for extended periods, retaining the capacity to react upon reexposure.
93
What are the **principal chemical mediators** produced by mast cells and basophils in allergic reactions?
* Histamine * Serotonin * Leukotriene * Platelet-activating factor * Prostaglandins * Bradykinin ## Footnote These mediators account for the wide range of allergic symptoms experienced.
94
Fill in the blank: The **general responses** of target organs to allergic mediators include _______.
* Rashes * Itching * Redness * Rhinitis * Sneezing * Diarrhea * Shedding of tears ## Footnote These responses vary based on the affected organ systems.
95
True or false: **Histamine** is the most profuse and fastest-acting allergic mediator.
TRUE ## Footnote Histamine is a potent stimulator of smooth muscle, glands, and eosinophils.
96
What effects does **histamine** have on smooth muscle in the bronchioles and intestines?
* Constricts smooth muscle in bronchioles (causing labored breathing) * Increases intestinal motility ## Footnote Histamine's actions vary depending on the location within the body.
97
What systemic targets are affected by mediators in allergic reactions?
* Smooth muscle * Mucous glands * Nervous tissue ## Footnote Changes in smooth muscle activity can significantly alter blood flow, blood pressure, and respiration.
98
What is the end result of the **allergic response** in various organs?
* Red, itchy eyes * Hives * Runny nose ## Footnote These symptoms arise from the physiological effects of mast cell mediators on target organs.
99
What is the role of **histamine** in allergic reactions?
* Dilates arterioles and venules * Causes wheal and flare reaction * Induces pruritis (itching) * Can lead to headache * In severe reactions, can cause edema, hypotension, tachycardia, circulatory failure, and shock ## Footnote Histamine targets salivary, lacrimal, mucous, and gastric glands.
100
What are the effects of **serotonin** in human allergy?
* Increases vascular permeability * Causes capillary dilation * Induces smooth muscle contraction * Stimulates intestinal peristalsis * Increases respiratory rate * Diminishes central nervous system activity ## Footnote The role of serotonin in human allergy is uncertain but appears to complement histamine.
101
What is the function of **leukotrienes** in allergic reactions?
* Induces gradual contraction of smooth muscle * Responsible for prolonged bronchospasm * Stimulates mucous secretion * Affects vascular permeability ## Footnote A type of leukotriene is known as the 'slow-reacting substance of anaphylaxis'.
102
What physiological responses are associated with **platelet-activating factor**?
* Increased vascular permeability * Pulmonary smooth muscle contraction * Pulmonary edema * Hypotension * Wheal and flare response in the skin ## Footnote Released by basophils, neutrophils, monocytes, and macrophages.
103
What are the effects of **prostaglandins** in allergic reactions?
* Vasodilation * Increased vascular permeability * Increased sensitivity to pain * Bronchoconstriction ## Footnote Prostaglandins also regulate smooth muscle contraction, such as stimulating uterine contractions during delivery.
104
True or false: **Histamine** is responsible for the wheal and flare reaction in the skin.
TRUE ## Footnote Histamine's role includes causing pruritis and headache, and in severe cases, it can lead to shock.
105
Fill in the blank: A **wheal** is a smooth, slightly elevated, temporary _______ surrounded by a flushed patch of skin.
welt ## Footnote The term 'wheal' is often associated with allergic reactions.
106
What symptoms are associated with **asthma** due to leukotrienes?
* Airway obstruction * Mucus buildup * Excessive mucus production * Wheezing * Difficult breathing * Coughing ## Footnote Leukotrienes contribute to the prolonged bronchospasm in asthmatic individuals.
107
What is **bradykinin** related to?
A group of plasma and tissue peptides known as kinins ## Footnote Kinins participate in blood clotting and chemotaxis.
108
What are the effects of **bradykinin** in allergy?
* Prolonged contraction of bronchioles * Dilation of peripheral arterioles * Increased capillary permeability * Increased mucus secretion ## Footnote These effects contribute to allergic reactions.
109
Name the **specific diseases** associated with IgE- and mast-cell-mediated allergy.
* Hay fever * Allergic asthma * Food allergy * Drug allergy * Eczema * Anaphylaxis ## Footnote These conditions are characterized by similar allergic mechanisms.
110
What is **hay fever** a generic term for?
Allergic rhinitis ## Footnote It can be seasonal or chronic, reacting to airborne allergens.
111
What are the **symptoms** of hay fever?
* Nasal congestion * Sneezing * Coughing * Profuse mucus secretion * Itchy, red, and teary eyes * Mild bronchoconstriction ## Footnote These symptoms target respiratory membranes.
112
What characterizes **allergic asthma**?
Episodes of impaired breathing due to severe bronchoconstriction ## Footnote Asthmatic airways are highly responsive to allergens and stimuli.
113
What are common **symptoms** of asthma?
* Labored breathing * Shortness of breath * Wheezing * Cough * Ventilatory rales ## Footnote Symptoms can range from mild to severe.
114
What is the estimated number of **asthma sufferers** in the United States?
More than 20 million ## Footnote Nearly one-third of asthma sufferers are children.
115
True or false: **Asthma** and deaths from it have been decreasing over the last 30 years.
FALSE ## Footnote Despite the availability of effective control agents, asthma cases and related deaths have been increasing.
116
In which regions is **asthma** more common?
Developed regions such as the United States and parts of Europe ## Footnote It is less common in less developed countries in Asia and Africa.
117
What environmental factors may influence the development of **allergies** and **asthma**?
* Indoor conditions in modern insulated buildings * Higher concentrations of airborne allergens * Ozone ## Footnote These factors suggest a connection between environment and respiratory health.
118
What is **atopic dermatitis** also known as?
eczema ## Footnote It is an intensely itchy inflammatory condition of the skin.
119
How does **sensitization** occur in atopic dermatitis?
* Ingestion * Inhalation * Skin contact with allergens ## Footnote Sensitization usually begins in infancy with skin lesions.
120
What are the common **symptoms** of atopic dermatitis?
* Itchy lesions * Reddish, vesicular skin * Weeping, encrusted skin lesions * Dry, scaly, thickened skin ## Footnote Lesions can occur on the face, scalp, neck, and limbs.
121
What are the **gastrointestinal symptoms** of food allergies?
* Vomiting * Diarrhea * Abdominal pain ## Footnote Severe cases can lead to poor nutrient absorption and growth retardation.
122
What are some **manifestations** of food allergies?
* Rashes * Hives * Rhinitis * Asthma * Anaphylaxis ## Footnote Classic food hypersensitivity involves IgE and mast cell degranulation.
123
What are the **most common food allergens**?
* Peanuts * Fish * Cow's milk * Eggs * Shellfish * Soybeans ## Footnote Introducing certain foods early may prevent sensitization in children.
124
True or false: **Food allergy** is the same as food intolerance.
FALSE ## Footnote Food intolerance, like lactose intolerance, is due to enzyme deficiencies.
125
What is a common side effect of **modern chemotherapy**?
Drug allergy ## Footnote Allergy to drugs is present in 5% to 10% of hospitalized patients.
126
What are some **compounds** often implicated in drug allergies?
* Antibiotics (penicillin) * Synthetic antimicrobials (sulfa drugs) * Aspirin * Opiates * Contrast dye ## Footnote The allergen is often a hapten produced when the liver processes the drug.
127
What is **anaphylaxis** characterized by?
* Itching * Sneezing * Difficult breathing * Prostration * Convulsions ## Footnote Anaphylaxis can be fatal within minutes.
128
What are the two clinical types of **anaphylaxis** seen in humans?
* Cutaneous anaphylaxis * Systemic anaphylaxis ## Footnote Systemic anaphylaxis is also called anaphylactic shock.
129
What is the difference between **cutaneous anaphylaxis** and systemic anaphylaxis?
Cutaneous anaphylaxis involves local reactions; systemic anaphylaxis involves respiratory and circulatory disruption ## Footnote Systemic anaphylaxis can be fatal in a few minutes.
130
What is one of the most frequent causes of **anaphylactic shock**?
Bee stings ## Footnote Honeybee and other hymenopteran stings are often implicated in anaphylactic reactions.
131
What can bee venom create that lasts for decades after exposure?
Sensitivity ## Footnote This sensitivity can lead to severe allergic reactions upon subsequent exposures.
132
In systemic anaphylaxis, what is released in a massive quantity by the immune system?
Chemical mediators ## Footnote This release acts rapidly on target organs, causing severe symptoms.
133
What happens to the throat during an **anaphylactic reaction**?
Swells ## Footnote This swelling can compromise respiration and lead to airway blockage.
134
What is the leading cause of death related to **food allergy**?
Peanut allergies ## Footnote These allergies are notorious for their rapid onset and small allergen doses.
135
True or false: Fatal cases of peanut allergies have occurred from merely kissing a person who had eaten peanuts.
TRUE ## Footnote Sharing a drinking glass that had contact with peanuts can also trigger fatal reactions.
136
What is important to determine when diagnosing an **allergy**?
If a person is actually allergic ## Footnote Identifying specific allergens is also helpful in the diagnosis.
137
What enzyme's elevated blood levels can indicate an **allergic attack**?
Tryptase ## Footnote This enzyme is released by mast cells during an allergic response.
138
What does a higher level of **basophils and eosinophils** indicate?
Allergy ## Footnote A differential blood cell count can reveal these elevated levels.
139
What test measures the amount of **histamine** released from basophils?
Leukocyte histamine-release test ## Footnote This test is used to determine allergy responses.
140
What technique can precisely detect **atopic or anaphylactic sensitivities**?
Skin testing ## Footnote This involves injecting, scratching, or pricking the skin with allergens.
141
What is the purpose of mapping the skin in patients with numerous allergies during skin testing?
To inject allergens intradermally ## Footnote This is done according to a predetermined pattern to assess reactions.
142
How is the **wheal response** measured after skin testing?
On a scale of 0 to 4+ ## Footnote A wheal greater than 15 mm indicates a strong histamine release.
143
What is a newer rapid test for allergies that has greater accuracy than skin testing?
Alternate system for testing ## Footnote This method does not require injection of allergens.
144
What are the **three methods** of treating and preventing allergy?
* Avoiding the allergen * Taking drugs that block lymphocytes, mast cells, or chemical mediators * Undergoing allergen desensitization therapy ## Footnote Avoidance may be difficult, and initial sensitization cannot be completely prevented.
145
What is the role of **corticosteroids** in allergy treatment?
Inhibit the activity of lymphocytes and reduce IgE production ## Footnote They have dangerous side effects and should not be taken for prolonged periods.
146
True or false: **Antihistamines** can cause drowsiness.
TRUE ## Footnote Many newer antihistamines lack this side effect as they do not cross the blood-brain barrier.
147
What is the purpose of **epinephrine** in allergy treatment?
Reverses airway constriction and slows the release of allergic mediators ## Footnote It is crucial for individuals experiencing anaphylactic attacks.
148
What is **desensitization** in the context of allergy treatment?
Controlled injections of specific allergens to prevent reactions ## Footnote Approximately 70% of allergic patients benefit from this technique.
149
What is the **newer experimental method** of hyposensitization?
Sublingual therapy ## Footnote Involves placing a tiny dose of allergen under the tongue for absorption.
150
What do **monoclonal antibodies** like omalizumab (Xolair) do?
Inactivate IgE ## Footnote They are used to help manage allergic symptoms.
151
What is the function of **cromolyn** in allergy treatment?
Acts on mast cell surfaces to prevent degranulation ## Footnote It helps reduce allergic reactions.
152
Fill in the blank: **Allergen desensitization therapy** is also known as __________.
hyposensitization ## Footnote This therapy prevents reactions between allergen, IgE, and mast cells.
153
What are the effects of **theophylline** in allergy treatment?
Reverses spasms in respiratory smooth muscles ## Footnote It is a bronchodilator used for asthma relief.
154
What is the role of **antihistamines** in allergy control?
Interfere with histamine activity by binding to histamine receptors ## Footnote They are commonly used in over-the-counter allergy medications.
155
What is the significance of **avoiding allergens** in allergy management?
It may be very difficult but is essential to prevent allergic reactions ## Footnote Complete isolation from allergens is not feasible.
156
What are the **Type II Hypersensitivities** characterized by?
* Reactions that lyse foreign cells * Involvement of antibodies (IgG and IgM) directed against surface antigens ## Footnote This includes transfusion reactions and some types of autoimmunities.
157
What is the role of **IgG blocking antibodies** in Type II Hypersensitivities?
* Remove allergen from the system before it binds to IgE * Prevent degranulation of mast cells ## Footnote They may also combine with IgE and take it from circulation.
158
What are **alloantigens**?
Molecules that differ in the same species ## Footnote They are introduced during blood transfusions and organ donations.
159
Who first demonstrated the existence of **human blood types**?
Karl Landsteiner ## Footnote He identified blood type incompatibilities during transfusion studies in 1904.
160
What are the **four ABO blood groups** identified by Landsteiner?
* Type A * Type B * Type AB * Type O ## Footnote These blood types are genetically determined and composed of glycoproteins.
161
What is the inheritance pattern of **ABO antigens**?
* A and B alleles are dominant over O * A and B alleles are codominant with each other ## Footnote This results in different blood types based on genotype combinations.
162
A person with an **AA or AO genotype** has what blood type?
Type A ## Footnote The blood type is named for the dominant antigen present.
163
What do the **RBCs of type O persons** lack?
A and B antigens ## Footnote However, they have other types of antigens.
164
What can complicate **organ transplantation** related to blood types?
Presence of A and B antigens in tissues other than RBCs ## Footnote This can lead to immune reactions during transplantation.
165
What are the **four blood types** based on the presence of A and B antigens?
* Type A * Type B * Type AB * Type O ## Footnote Each blood type is determined by the presence or absence of specific antigens on the surface of red blood cells.
166
What do **Type A** red blood cells contain that distinguishes them from other types?
An enzyme that adds N-acetylgalactosamine ## Footnote This enzyme modifies the basic RBC receptor to create the A antigen.
167
What do **Type B** red blood cells contain that distinguishes them from other types?
An enzyme that adds D-galactose ## Footnote This enzyme modifies the basic RBC receptor to create the B antigen.
168
What do **Type AB** red blood cells contain that distinguishes them from other types?
Both enzymes that add N-acetylgalactosamine and D-galactose ## Footnote This allows Type AB blood to express both A and B antigens.
169
What do **Type O** red blood cells lack?
Genes and enzymes to add a terminal molecule ## Footnote Type O blood is not antigenic and does not have A or B antigens.
170
True or false: Type A blood contains antibodies against **B antigens**.
TRUE ## Footnote Type A blood has anti-B antibodies that react with B antigens on Type B and AB red blood cells.
171
What type of antibodies does **Type O** blood contain?
* Anti-A antibodies * Anti-B antibodies ## Footnote Type O blood contains antibodies against both A and B antigens.
172
How do antibodies against A and B antigens develop in individuals?
Through exposure to certain antigens in early infancy ## Footnote These antigens mimic A and B antigens and stimulate antibody production.
173
What is the **general rule of compatibility** for blood transfusions?
The RBC antigens of the donor must not be agglutinated by antibodies in the recipient's blood ## Footnote This ensures safe transfusions and prevents transfusion reactions.
174
What is the purpose of mixing blood with **antisera** during blood typing?
To observe for evidence of agglutination ## Footnote Agglutination indicates the presence of specific antigens on the red blood cells.
175
What is the **universal donor** blood type?
Type O ## Footnote Type O blood lacks A and B antigens and can theoretically be used in any transfusion.
176
What is the **universal recipient** blood type?
Type AB ## Footnote Individuals with type AB blood lack agglutinating antibodies and can receive any type of blood.
177
What are the **three major blood group incompatibilities** that can be significant in transfusions?
* ABO * Rh * Kell ## Footnote These incompatibilities can lead to serious transfusion reactions.
178
True or false: **Transfusion reactions** are very common due to blood type mismatches.
FALSE ## Footnote Incorrect transfusions are rare because blood banks take great care to ensure correct matches.
179
What happens during a **transfusion reaction**?
* Agglutination of donor cells * Blockage of circulation in vital organs * Activation of complement leading to hemolysis ## Footnote These reactions can lead to systemic shock and kidney failure.
180
What is the **Rh factor** also known as?
D antigen ## Footnote The Rh factor is present in about 85% of humans and is significant in blood transfusions.
181
Fill in the blank: A person inheriting at least one Rh gene will be _______.
Rh+ ## Footnote Only those inheriting no Rh genes are Rh-.
182
What condition can occur when an Rh- mother has an Rh+ fetus during pregnancy?
Hemolytic Disease of the Newborn (HDN) ## Footnote This condition can lead to severe complications for the fetus in subsequent pregnancies.
183
What is **erythroblastosis fetalis**?
A potentially fatal hemolytic disease of the newborn ## Footnote It is characterized by the presence of immature nucleated RBCs in the blood.
184
What is the primary cause of **maternal sensitization** to the Rh factor?
Fetal RBCs leaking into the mother's circulation ## Footnote This can occur during childbirth when the placenta detaches.
185
What must be done before a blood transfusion to prevent reactions?
Cross-matching blood samples ## Footnote This test checks for agglutination between donor blood and recipient serum.
186
What are the **additional symptoms** of RBCs stimulated by maternal antibodies?
* Severe anemia * Jaundice * Enlarged spleen * Enlarged liver ## Footnote These symptoms are associated with hemolytic disease of the newborn.
187
Maternal-fetal incompatibilities in the **ABO blood group** occur less frequently than with **Rh sensitization** because the antibodies are primarily what type?
IgM ## Footnote IgM antibodies are unable to cross the placenta in large numbers.
188
What forms a barrier to keep the fetus isolated in its own **antigen-free environment**?
The placenta ## Footnote The placenta is surrounded by a dense, many-layered envelope that prevents the passage of maternal cells.
189
What is required to prevent **hemolytic disease of the newborn** once sensitization of the mother to Rh factor has occurred?
A careful family history of an Rh pregnant woman ## Footnote This helps predict the likelihood of sensitization or carrying an Rh+ fetus.
190
If the father is **Rh***, what is the probability that the child will be **Rht**?
* 50% * 100% ## Footnote This depends on the exact genetic makeup of the father.
191
What must be administered to the mother if there is any possibility that the fetus is **Rh***?
RhoGAM ## Footnote RhoGAM is an antiserum containing antibodies against the Rh factor, injected at 28 to 32 weeks and after delivery.
192
What is the purpose of **RhoGAM**?
Keeps the maternal immune system from recognizing fetal RBCs ## Footnote This prevents sensitization to the Rh factor.
193
True or false: **Anti-Rh antibody** must be given with each pregnancy that involves an Rh+ fetus.
TRUE ## Footnote It is ineffective if the mother has already been sensitized.
194
What should be matched for a **transfusion**?
The Rh factor ## Footnote It is acceptable to transfuse Rh blood if the recipient's Rh type is unknown.
195
What is the **mechanism of type II hypersensitivity**?
Not specified in the text ## Footnote This question prompts further exploration of hypersensitivity mechanisms.
196
Explain why the tissues of some people are **antigenic** to others.
Not specified in the text ## Footnote This question relates to transfusions and transplants.
197
What is the **molecular basis** of the ABO and Rh blood groups?
Not specified in the text ## Footnote This question encourages investigation into blood group antigens.
198
Where do we derive our **natural hypersensitivities** to the A or B antigens that we do not possess?
Not specified in the text ## Footnote This question addresses the origin of natural antibodies.
199
How does a person become **sensitized** to Rh factor?
when an Rh-negative individual is exposed to Rh-positive red blood cells, causing their immune system to see the Rh (D) antigen as foreign and make antibodies against it.
200
Describe the **sequence of events** in an Rh incompatibility between mother and fetus.
Mother is Rh-negative • Fetus is Rh-positive • Fetal blood enters mother’s circulation • Mother becomes sensitized • Mother makes anti-D antibodies • In next Rh-positive pregnancy: • Antibodies cross placenta • Fetal RBCs are destroyed • Causes hemolytic disease of the newborn
201
What will happen if **type A blood** is accidentally transfused into a **type B person**?
If type A blood is transfused into a type B person, it can cause a severe, potentially life-threatening transfusion reaction.
202
What is **Type III hypersensitivity** characterized by?
Reaction of soluble antigen with antibody and deposition of complexes in basement membranes ## Footnote It involves the production of IgG and IgM antibodies after repeated exposure to antigens.
203
How does **Type III hypersensitivity** differ from **Type II hypersensitivity**?
Type III involves free-floating complexes, while Type II has antigens attached to cell surfaces ## Footnote Type III leads to immune complex reactions or diseases.
204
List examples of **immune complex diseases**.
* Serum sickness * Arthus reaction * Glomerulonephritis * Lupus erythematosus ## Footnote These diseases are associated with the deposition of immune complexes in tissues.
205
What triggers the **inflammatory response** in immune complex diseases?
Antigen-antibody complexes summon inflammatory components like complement and neutrophils ## Footnote These components normally eliminate Ab-Ag complexes as part of the immune response.
206
What are the **characteristics** that differentiate serum sickness and the Arthus reaction from anaphylaxis?
* Depend on IgG, IgM, or IgA * Require large doses of antigen * Symptoms delayed by hours to days ## Footnote Anaphylaxis requires small doses of antigen and involves IgE.
207
Describe the **Arthus reaction**.
Localized dermal injury due to inflamed blood vessels from injected antigen ## Footnote Symptoms include redness, swelling, and pain at the injection site.
208
What are the **symptoms** of the Arthus reaction?
* Redness * Swelling * Pain * Heat ## Footnote These symptoms result from tissue destruction and histamine release.
209
What can occasionally cause **necrosis** in the Arthus reaction?
Intravascular blood clotting ## Footnote This can lead to loss of tissue in severe cases.
210
What is the **pathology** of immune complex disease?
Deposition of circulating Ab-Ag complexes in tissues leads to major organ damage ## Footnote This occurs in blood vessels, kidneys, skin, and other sites.
211
What is the **role of neutrophils** in immune complex diseases?
Migrate to sites of Ab-Ag complexes and release enzymes and chemokines ## Footnote This action severely damages target tissues and organs.
212
What is **serum sickness** associated with?
* Repeated injections of horse serum * Injections of animal hormones and drugs ## Footnote Serum sickness can cause chronic symptoms like enlarged lymph nodes, rashes, and renal dysfunction.
213
What are the **symptoms** of serum sickness?
* Enlarged lymph nodes * Rashes * Painful joints * Swelling * Fever * Renal dysfunction ## Footnote These symptoms arise from immune complexes deposited in various body tissues.
214
Contrast **type II** and **type III hypersensitivities** with respect to type of antigen, antibody, and manifestations of disease.
N/A ## Footnote This question prompts a detailed comparison of the two types of hypersensitivities.
215
Define **type IV hypersensitivities**.
Hypersensitivity involving primarily T cells ## Footnote Symptoms arise 1 to several days after contact with an antigen.
216
What are examples of **type IV hypersensitivity**?
* Delayed allergic reactions to infectious agents * Contact dermatitis * Graft rejection ## Footnote These reactions involve T cells responding to antigens on self tissues or transplanted cells.
217
What is a classic example of **delayed-type hypersensitivity**?
Tuberculin reaction ## Footnote This occurs when a sensitized person is injected with tuberculin from Mycobacterium tuberculosis.
218
What is the **tuberculin reaction**?
Acute skin inflammation at the injection site ## Footnote It appears within 24 to 48 hours and is used for tuberculosis screening.
219
What type of T cells are involved in the **tuberculin reaction**?
TH1 cells ## Footnote These cells receive processed allergens from dendritic cells and release cytokines.
220
What causes **contact dermatitis**?
* Exposure to resins in poison ivy or poison oak * Simple haptens in household articles * Certain drugs ## Footnote It is the most common delayed allergic reaction.
221
What is the role of **Langerhans cells** in contact dermatitis?
Process allergens and present them to T cells ## Footnote This initiates the immune response leading to dermatitis.
222
What are the early symptoms of **contact dermatitis**?
* Itchy papules * Blisters ## Footnote These symptoms result from the immune response to allergens.
223
What is the **time frame** for healing in contact dermatitis?
Up to 2 weeks ## Footnote Healing time varies based on dose and individual sensitivity.
224
What is the **primary challenge** in organ transplantation?
Graft rejection due to lymphocyte response ## Footnote Lymphocytes seek out foreign antigens and mount an immune response.
225
What cells are primarily responsible for **graft rejection**?
* Cytotoxic T cells * Other killer cells ## Footnote These cells are activated to destroy foreign tissues.
226
What is the role of **MHC genes** in graft rejection?
Recognize self and regulate immune response ## Footnote MHC genes set the events of graft rejection in motion.
227
What is **serum sickness** associated with?
* Repeated injections of horse serum * Injections of animal hormones and drugs ## Footnote Serum sickness can cause chronic symptoms like enlarged lymph nodes, rashes, and renal dysfunction.
228
What are the **symptoms** of serum sickness?
* Enlarged lymph nodes * Rashes * Painful joints * Swelling * Fever * Renal dysfunction ## Footnote These symptoms arise from immune complexes deposited in various body tissues.
229
Contrast **type II** and **type III hypersensitivities** with respect to type of antigen, antibody, and manifestations of disease.
N/A ## Footnote This question prompts a detailed comparison of the two types of hypersensitivities.
230
Define **type IV hypersensitivities**.
Hypersensitivity involving primarily T cells ## Footnote Symptoms arise 1 to several days after contact with an antigen.
231
What are examples of **type IV hypersensitivity**?
* Delayed allergic reactions to infectious agents * Contact dermatitis * Graft rejection ## Footnote These reactions involve T cells responding to antigens on self tissues or transplanted cells.
232
What is a classic example of **delayed-type hypersensitivity**?
Tuberculin reaction ## Footnote This occurs when a sensitized person is injected with tuberculin from Mycobacterium tuberculosis.
233
What is the **tuberculin reaction**?
Acute skin inflammation at the injection site ## Footnote It appears within 24 to 48 hours and is used for tuberculosis screening.
234
What type of T cells are involved in the **tuberculin reaction**?
TH1 cells ## Footnote These cells receive processed allergens from dendritic cells and release cytokines.
235
What causes **contact dermatitis**?
* Exposure to resins in poison ivy or poison oak * Simple haptens in household articles * Certain drugs ## Footnote It is the most common delayed allergic reaction.
236
What is the role of **Langerhans cells** in contact dermatitis?
Process allergens and present them to T cells ## Footnote This initiates the immune response leading to dermatitis.
237
What are the early symptoms of **contact dermatitis**?
* Itchy papules * Blisters ## Footnote These symptoms result from the immune response to allergens.
238
What is the **time frame** for healing in contact dermatitis?
Up to 2 weeks ## Footnote Healing time varies based on dose and individual sensitivity.
239
What is the **primary challenge** in organ transplantation?
Graft rejection due to lymphocyte response ## Footnote Lymphocytes seek out foreign antigens and mount an immune response.
240
What cells are primarily responsible for **graft rejection**?
* Cytotoxic T cells * Other killer cells ## Footnote These cells are activated to destroy foreign tissues.
241
What is the role of **MHC genes** in graft rejection?
Recognize self and regulate immune response ## Footnote MHC genes set the events of graft rejection in motion.
242
What are **chemical antigens** involved in immunopathologies?
* Nickel * Sulfate * Colophonium * Cobalt II Chloride ## Footnote These substances can induce allergic reactions in sensitive individuals.
243
What is the role of **dendritic cells** in the immune response?
Pick up allergens, process them, and display them on MHC receptors ## Footnote Dendritic cells are crucial for activating T cells in response to allergens.
244
Fill in the blank: **Sensitized TH1 cells** secrete _______ to attract macrophages and cytotoxic T cells.
cytokines (IFN, TNF) ## Footnote These cytokines play a key role in the inflammatory response.
245
What do **cytotoxic T cells** do in the immune response?
Directly kill cells and damage the skin ## Footnote This action contributes to the formation of fluid-filled blisters in contact dermatitis.
246
What is the process of **patch testing** for contact dermatitis?
Allergen-impregnated patches are applied to the skin for 48 hours ## Footnote This method helps identify specific allergens causing dermatitis.
247
True or false: **Host rejection of graft** occurs when T cells recognize foreign class I MHC markers.
TRUE ## Footnote This immune response can lead to the destruction of transplanted tissues.
248
What happens during the **graft rejection** process?
* T cells release interleukin-2 * Expansion of helper and cytotoxic T cells * Binding to grafted tissue * Secretion of lymphokines ## Footnote These actions initiate the rejection process within 2 weeks of transplantation.
249
What can prevent the host from rejecting a graft in cases of **immunodeficiencies**?
Certain types of immunodeficiencies ## Footnote However, this may not protect the host from serious damage.
250
What is the consequence of **graft incompatibility**?
It is a two-way phenomenon that can lead to serious damage ## Footnote Grafted tissues can also attack the host's immune system.
251
What is **graft versus host disease (GVHD)**?
A condition where the graft attacks the host due to foreign MHC markers ## Footnote Symptoms include a papular, peeling skin rash and can affect the liver, intestine, muscles, and mucous membranes.
252
What percentage of **bone marrow transplants** previously experienced GVHD?
Approximately 30% ## Footnote This percentage is declining due to better screening and selection of tissues.
253
Define **autograft**.
Tissue transplanted from one site to another on an individual's body ## Footnote Examples include skin replacement in burn repair and using a vein for coronary artery bypass.
254
What is an **isograft**?
Tissue from an identical twin ## Footnote Isografts are not rejected as they do not contain foreign antigens.
255
What are **allografts**?
Tissue exchanges between genetically different individuals of the same species ## Footnote Allografts are the most common type of grafts.
256
Define **xenograft**.
A tissue exchange between individuals of different species ## Footnote Most xenografts are experimental or for temporary therapy only.
257
What is the purpose of **tissue matching procedures**?
To compare the tissue of the recipient with that of potential donors ## Footnote This helps to avoid or control graft rejection.
258
What does the **mixed lymphocyte reaction (MLR)** involve?
Mixing and incubating lymphocytes from two individuals ## Footnote Activation and proliferation of cells indicate incompatibility.
259
What is **tissue typing** similar to?
Blood typing ## Footnote It is used to assess compatibility between donor and recipient tissues.
260
What is the role of **cytotoxic T cells** in transplantation?
Mediates the rejection of the organ ## Footnote Cytotoxic T cells encounter the cells of the donated organ and initiate an immune response.
261
What are the two types of **graft reactions** mentioned?
* Host rejecting the graft * Graft rejecting the host ## Footnote These reactions can lead to complications in transplantation procedures.
262
In most grafts, what must be matched besides HLA antigens?
ABO blood type ## Footnote A closer match increases the likelihood of transplant success.
263
How many transplants take place each year in the **United States**?
More than 100,000 ## Footnote Transplantation is a recognized medical procedure performed on major organs.
264
What are the most frequent transplant operations?
* Skin * Liver * Heart * Kidney * Coronary artery * Cornea * Blood stem cells ## Footnote These operations involve various sources, including live donors and cadavers.
265
What is **allogeneic hematopoietic stem cell transplantation** used for?
* Immune deficiencies * Aplastic anemia * Leukemia * Other cancers * Radiation damage ## Footnote This procedure is common but has a high mortality rate.
266
What are the three primary sources of **stem cells** used in transplantation?
* Bone marrow * Peripheral blood * Umbilical cord blood ## Footnote These sources are critical for treating severe medical conditions.
267
What procedure is performed to prepare recipients for a **bone marrow transplant**?
* Chemotherapy * Whole-body irradiation ## Footnote This is done to destroy the recipient's own blood stem cells to prevent rejection.
268
What is a surprising consequence of **bone marrow transplantation**?
A recipient's blood type may change to that of the donor ## Footnote This occurs due to the integration of donor stem cells.
269
What is **leukapheresis**?
The process of selectively removing and collecting WBCs from circulating blood ## Footnote This technique is used to harvest stem cells directly from blood donors.
270
What is an advantage of using **umbilical cord blood** for stem cell transplants?
Less likely to cause transplant rejections ## Footnote Cord blood stem cells have not developed the donor's receptors.
271
What is the general pathology of **autoimmune diseases**?
* Hypersensitivity to own cells * Autoantibodies and T cells attack self-antigens * Can be systemic or organ-specific ## Footnote Autoimmune diseases are categorized as II or III hypersensitivity based on how autoantibodies cause injury.
272
What factors influence the **susceptibility** to autoimmune diseases?
* Genetics * Gender * Environmental factors ## Footnote Cases often cluster in families, and unaffected members may still develop autoantibodies for the disease.
273
Which gender is more often affected by **autoimmune diseases**?
Females ## Footnote Autoimmune diseases, except ankylosing spondylitis, are more common in females, particularly during childbearing years.
274
What is the **sequestered antigen theory** in relation to autoimmune diseases?
* Some tissues are immunologically privileged * Tissues are sequestered behind anatomical barriers * Examples include CNS, lens of the eye, thyroid, and testes ## Footnote This theory suggests that exposure of these antigens can trigger autoimmune responses.
275
True or false: Autoantibodies are always harmful and indicate disease.
FALSE ## Footnote Low levels of autoantibodies are normal and may help dispose of old cells and debris.
276
What are the two main categories of **autoimmune diseases** based on their scope?
* Systemic * Organ-specific ## Footnote Systemic diseases affect multiple organs, while organ-specific diseases target a single organ or tissue.
277
What is the relationship between **major histocompatibility gene complexes** and autoimmune diseases?
* Certain genes coincide with specific autoimmune diseases * Examples include rheumatoid arthritis and ankylosing spondylitis ## Footnote These genes are found in class I and class II major histocompatibility complexes.
278
Fill in the blank: Autoimmune diseases usually fall into categories II or III **________**.
hypersensitivity ## Footnote This classification is based on how autoantibodies cause injury.
279
According to the **clonal selection theory**, how does the immune system develop tolerance to self?
* Eradicating or silencing self-reactive lymphocyte clones * Retaining clones that react to foreign antigens ## Footnote Some hidden clones may survive and attack tissues carrying self molecules, mistaking them for antigens.
280
What are the two main proposals of the **theory of immune deficiency**?
* Mutations in receptor genes of lymphocytes render them reactive to self * Dysfunctional T-cell regulatory cells that maintain tolerance to self ## Footnote These factors can lead to autoimmunity.
281
What is the **bystander effect** in the context of autoimmune diseases?
T-cell activation mistakenly turns on B cells that react with self antigens ## Footnote This can lead to inappropriate immune responses against the body's own tissues.
282
What is **molecular mimicry** and how does it relate to autoimmune diseases?
Microbial antigens bear molecular determinants similar to normal human cells ## Footnote This can stimulate antibodies that cross-react with tissues, potentially causing diseases like rheumatic fever and psoriasis.
283
Name two autoimmune diseases likely triggered by **viral infection**.
* Type I diabetes * Multiple sclerosis ## Footnote Viruses can alter cell receptors, causing immune cells to attack tissues.
284
What is **systemic lupus erythematosus** (SLE) characterized by?
* Butterfly-shaped facial rash * Autoantibodies against various organs and tissues * Symptoms like kidney failure and skin lesions ## Footnote SLE often cycles between flare-ups and remission.
285
What is the predominant symptom of **rheumatoid arthritis** (RA)?
Progressive, debilitating damage to the joints ## Footnote RA can also involve the lungs, eyes, skin, and nervous systems.
286
In SLE, what type of complexes are deposited in the basement membranes of various organs?
Autoantibody-autoantigen complexes ## Footnote This can lead to symptoms like kidney failure and lung inflammation.
287
What is the common feature of rheumatoid arthritis (RA)?
Presence of IgM antibody called rheumatoid factor (RF) ## Footnote RF is directed against the synovial membrane of the joints.
288
True or false: The etiology of **lupus** is completely understood.
FALSE ## Footnote The exact cause of lupus is still not known, though viral infection and loss of T-cell suppressor function are suspected.
289
What treatments are commonly used to control flare-ups of **systemic lupus erythematosus**?
* Steroids * Methotrexate * Monoclonal antibody belimumab (Benlysta) ## Footnote These treatments aim to manage symptoms and reduce flare-ups.
290
What are the **two types of immunities** affected by primary immunodeficiency diseases?
* Specific immunities (e.g., antibody production) * Less-specific immunities (e.g., phagocytosis) ## Footnote Deficiencies can occur at various stages in the development of lymphocytes.
291
What is the term for the **absence of gamma globulin**?
Agammaglobulinemia ## Footnote Some physicians prefer the term *hypogammaglobulinemia* due to the rarity of complete absence of Ig.
292
What are the common **infection sites** for patients with agammaglobulinemia?
* Lungs * Sinuses * Meninges * Blood ## Footnote Patients often experience recurrent, serious bacterial infections starting around 6 months after birth.
293
What is the most prevalent **immunoglobulin deficiency**?
IgA deficiency ## Footnote Occurs in about 1 person in 600 and leads to recurrent respiratory and gastrointestinal infections.
294
True or false: **T-cell deficiencies** can lead to severe opportunistic infections, wasting, and cancer.
TRUE ## Footnote T helper cells are crucial for assisting in most specific immune reactions.
295
What is the disease associated with **thymic dysfunction**?
DiGeorge syndrome ## Footnote This condition is caused by failure in the embryonic development of the third and fourth pharyngeal pouches.
296
What are the possible consequences of **deficiencies in lymphocyte development**?
* Complete absence of lymphocytes * Low levels of lymphocytes * Non-functional lymphocytes ## Footnote Some deficiencies can affect other cell functions as well.
297
What type of **therapy** is available for patients with immunoglobulin deficiencies?
* Passive immunotherapy with immune serum globulin * Continuous antibiotic therapy ## Footnote These treatments aim to improve the prognosis of affected individuals.
298
What is a common **bacterial infection** implicated in patients with immunoglobulin deficiencies?
* Pyogenic cocci * Pseudomonas * Haemophilus influenzae ## Footnote These bacteria are often responsible for recurrent infections in these patients.
299
What is associated with **deletion mutation in chromosome 22** in relation to the fourth pharyngeal pouches?
DiGeorge syndrome ## Footnote This syndrome affects thymic function and immune activity.
300
What are the adverse effects on thymic function in DiGeorge syndrome?
* Reduced immune activity * Complete lack of cell-mediated immunity ## Footnote Especially affects CD4 or helper class of T cells.
301
Children with DiGeorge syndrome are highly susceptible to persistent infections by which types of pathogens?
* Fungi * Protozoa * Viruses ## Footnote Common childhood infections can be fatal if not treated promptly.
302
What can pose a danger to children with DiGeorge syndrome during vaccinations?
Vaccinations using attenuated microbes ## Footnote The lack of antibodies due to deficiencies in helper T cells increases risk.
303
What are some other symptoms of **DiGeorge syndrome**?
* Heart defects * Reduced growth * Wasting of the body * Unusual facial characteristics * Increased incidence of lymphatic cancer ## Footnote These symptoms vary in severity among affected individuals.
304
What is the only therapy that could restore the immune system in DiGeorge syndrome?
Thymus transplant ## Footnote Other conditions may be managed with surgery and drugs.
305
What are **Severe Combined Immunodeficiencies (SCIDs)** characterized by?
Loss of both T and B lymphocyte functions ## Footnote SCIDs are among the most severe immunodeficiency diseases.
306
What can cause SCIDs?
* Complete absence of lymphocyte stem cell in the marrow * Dysfunction of B cells and T cells later in development ## Footnote These factors lead to severe immune deficiencies.
307
When do infants with SCIDs usually manifest T-cell deficiencies?
Within days after birth ## Footnote Symptoms can develop rapidly, indicating severe immune dysfunction.
308
What is the **condition** characterized by compromised immune responses leading to increased susceptibility to infections?
Immunodeficiency diseases ## Footnote These diseases can be due to genetic defects or acquired factors.
309
Name the two most common forms of **severe combined immunodeficiency (SCID)**.
* Swiss-type agammaglobulinemia * Thymic aplasia ## Footnote Both forms result in diminished blood antibody content and poorly developed immunity.
310
What is the rare form of SCID caused by an autosomal recessive defect in the metabolism of adenosine?
Adenosine deaminase (ADA) deficiency ## Footnote This condition leads to the destruction of lymphocytes due to a buildup of metabolic products.
311
True or false: **X-SCID** is a deficiency in interleukin receptors that occurs equally in males and females.
FALSE ## Footnote X-SCID is X-linked and occurs most often in male infants.
312
What was the name of the child known for living in a sterile environment due to SCID?
David Vetter ## Footnote His case provided insights into the disease and its treatment.
313
What type of transplant is now preferred for long-term survival in SCID patients?
Bone marrow or stem cell transplant ## Footnote This is done immediately after diagnosis rather than placing them in sterile environments.
314
What are the four general agents that cause **secondary acquired deficiencies** in B and T cells?
* Infection * Organic disease * Chemotherapy * Radiation ## Footnote These factors can lead to immunodeficiency in individuals.
315
What is the most recognized infection-induced immunodeficiency?
Acquired immunodeficiency syndrome (AIDS) ## Footnote AIDS is caused by the human immunodeficiency virus (HIV) affecting various immune cells.
316
Define **cancer**.
New growth and spread of abnormal cells ## Footnote Cancer is also known as neoplasm and is characterized by uncontrolled cell growth.
317
What distinguishes a **malignant tumor** from a benign tumor?
Uncontrolled growth of abnormal cells within normal tissue ## Footnote Malignant tumors can invade adjacent tissues and are generally more dangerous.
318
What is the field of medicine that specializes in cancer called?
Oncology ## Footnote Oncology focuses on the diagnosis and treatment of cancer.
319
What is a **benign tumor**?
A self-contained mass within an organ that does not spread ## Footnote Benign tumors are usually slow-growing and not life-threatening unless they affect critical areas.
Microbiology
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