tarry-sky pattern is seen in which one of the following lymphomas?
= B ) Burkitt’s lymphoma
A 56-year-old man was admitted with sudden onset severe hypotension, widespread urticaria, and angioedema following a wasp sting. Anaphylaxis was suspected and treated appropriately according to the Resuscitation Council guidance. One of the nurses took some extra blood while inserting a spare cannula during resuscitation and asks you if you want any tests done.
Which blood test should be taken as soon as possible during the management of acute anaphylaxis?
= A ) Mast-cell tryptase
Investigation of a suspected anaphylactic reaction requires measurement of ___ levels.
= D ) Tryptase
Mast-cell tryptase blood tests should be taken immediately, 1-2 hours post event and 24 hours post event. Prolonged observation is not required in patients that have recovered completely, but they should be advised of the possibility of a biphasic reaction.
What disease is mediated by type II hypersensitivity?
Answer: Autoimmune hemolytic anaemia
The ‘wheal and flare’ reaction is seen in which type of hypersensitivity reaction?
= A ) Type I
IgA antibody is the first line of defence against infections at the mucous membrane. It is usually an early specific antibody.
Which of the following statements regarding IgA is true?
Answer: IgA is present in colostrum
Each secretory IgA molecule has a molecular weight of 400,000 and consists of two H2L2 units and one molecule each of J chain and secretory component. Some IgA exists in serum as a monomer H2L2 with a molecular weight of 160,000. Some bacteria, such as Neisseria, can destroy IgA1 by producing protease. It is the major immunoglobulin in milk, saliva, tears, and colostrum. IgA does not fix complement, so one would anticipate that a complement fixation test would not be useful for IgA antibody.
Individuals with allergic rhinitis who are exposed to an allergen will within minutes experience symptoms of nasal itching, nasal congestion, sneezing, and a runny nose. These symptoms generally subside within 30 minutes, but reappear several hours later. Analysis of the nasal epithelium in such an individual 6 hours after allergen encounter would show:
= C ) Infiltration of eosinophils, basophils, neutrophils, T cells, and macrophages
Which type of ultraviolet light causes most skin cancers?
= B ) UVB
UVC is the most dangerous ultraviolet wavelength but is mostly absorbed in the ozone layer.
Immunity may be natural or acquired. Which of the following best describes acquired immunity?
= D ) Maternal transfer of antibody
Natural immunity is nonspecific. The description of natural immune functions described are not specific for a certain antigen. For example, certain proteins such as C-reactive protein (CRP) are acute-phase reactants. While elevated CRP is seen in infection, it is not disease-specific. Maternal transfer of antibody, however, is passive but still confers specific immunity. It is termed acquired immunity.
What disease is mediated by type IV hypersensitivity?
= D ) MS
Which immunoglobulin class is found on the surface of mast cells?
= C ) IgE
What is a highly variable autoimmune disease mediated by type III hypersensitivity?
= G ) Rheumatoid arthritis
Which immunoglobulin class is a major component of mucosal secretions?
Answer: IgA
The major immunoglobulin class in normal adult human serum is:
Answer: IgG
Individuals with peanut allergies can exhibit a variety of symptoms following exposure to the peanut allergen. These symptoms can include a runny nose; skin reactions such as hives; itching in the mouth and throat; digestive problems such as cramps, diarrhea or vomiting; and respiratory problems such as wheezing and shortness of breath. This variety of symptoms is the result of:
Answer: The presence of mast cells with pre-bound IgE in all mucosal tissues
Unlike other antibody isotypes, IgE is found almost exclusively bound to the surface of mast cells and basophils. Mast cells are present in all mucosal tissues and, if pre-bound to allergen-specific IgE, encounter with the allergen will trigger mast cell activation and degranulation. Depending on the levels of allergen, the amounts of allergen-specific IgE, and the route of allergen entry, different individuals can exhibit some or all of these allergic symptoms.
Immune privileged sites, such as the brain, the eye, and the testis, are often the targets of autoimmune attack. Thus, once effector T cells are generated that have specificity for autoantigens expressed in these tissues, the effector cells can gain entry to the tissue and cause tissue damage. However, under normal circumstances, the priming and differentiation of effector cells specific for antigens found in the brain, for example, is generally prevented. This is because ‘immune privileged’ sites:
Answer: Express the cytokine, TGF-β
A 32-year-old male is found to have recurrent haematuria since his youth. The haematuria typically occurs with upper respiratory tract infections, especially sore throats. Vital signs are normal. Urinalysis shows proteinuria, haematuria and a few red blood cell casts. Laboratory studies disclose normal levels of urea and creatinine and tests for antinuclear antibody and antineutrophil cytoplasmic antibody are negative.
What is the likely diagnosis?
= C ) IgA nephropathy
Type I hypersensitivity reactions are mediated by which immunoglobulin?
= C ) IgE
Which of the following is true regarding the combined oral contraceptive pill?
Answer: An active pill is taken for 21 days and then a sugar pill is taken for 7 days
= E ) IgM
A newborn infected with group B streptococcus would produce and secrete antibody of which of the following class(es)?
= E ) IgM
A normal newborn can make IgM antibody in response to challenge with antigen. If IgG is detected in the newborn, it is most likely the result of placental transfer from the mother.
Which immunoglobulin class can cross the placenta?
Answer: IgG
In individuals with a peanut allergy, a mild allergic response is defined those that involve a only single site, typically a skin reaction (such as hives). More severe allergic reactions generally involve multiple tissue sites, such as the skin, oral mucosa, airway mucosa, and gastrointestinal tract. Given the two groups of allergic patients, one with only skin responses, and the other with 3–4 different tissue sites involved, one would expect that:
Answer: Patients with the severe allergic responses would have higher concentrations of allergen-specific IgE.
A child stung by a bee experiences respiratory distress within minutes, and lapses into unconsciousness. This reaction is probably mediated by:
= C ) IgE