Week 2 B Cells Flashcards Preview

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Flashcards in Week 2 B Cells Deck (26)
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1
Q

What are 4 components of the innate immune system?

A
  1. Physical barriers: skin, mucosal membranes
  2. Innate immune cells: neutrophils, monocytes, macrophages, eosinophils, basophils, NK cells and dendritic cells
  3. Circulating effector proteins
    a, Complement system
    b, Antimicrobial peptides & proteins
  4. Cytokines
2
Q

What is TNF alpha important for?

A

An important cytokine of innate immunity

Released by activated phagocytes

Recruits neutrophils and monocytes

Induces fever, leads to liver synthesis of actue-phase proteins

3
Q

What is the important aspect of the C-reactive protein (CRP)?

A

An important antimicrobial peptide, it performs opsonization and activation of complement system

In medicine it is used as an inflammation marker

4
Q

C3b does what?

A

Peforms opsonization of pathogens, even more effective than antibodies

5
Q

What complement components are responsible for the membrane-attack complex?

A

C5b, C6, C7, C8, C9

6
Q

What are the cellular components of the adaptive immune system?

A

Lymphocytes: T and B cells

7
Q

What cells of the innate immune response connect it to the adaptive immune response?

A

Dendritic cells

Mononuclear phagocytes

8
Q

What are the primary lymphoid organs?

A

Bone marrow:

  • source of lymphocyte progenitors
  • maturation of B cells

Thymus

  • maturation of T cells
9
Q

What are the secondary lymphoid organs?

A

Spleen - doesn’t make blood cells!

  • collects antigens from the blood
  • initiates adaptive immune responses

Lymph nodes

  • collect antigens from tissues
  • initiate adaptive immune responses

Cutaneous/mucosal ‘immune tissues’ (e.g. Peyer’s patches)

10
Q

What region of the lymph nodes contains mostly B cells?

What region for mostly T cells?

A

B cells - primary lymphoid follicles

T cells - paracortical area

11
Q

What is different about the specificity of the adaptive immune system, as opposed to the innate system?

A

T and B cells are specific for a large variety of antigens (epitopes)

12
Q

What is different about the diversity of the adaptive immune system, as opposed to the innate system?

A

Clone-specific receptors (not present in the germline)

(VDJ recombination)

13
Q

How do cells of the adaptive immune system reproduce in a way that creates an immunlogical memory?

A

“Clonal Expansion”

it takes 4-5 days before clonal expansion is complete and the lymphocytes have differentiated into effector cells, and so the first adaptive immune response to a pathogen only occurs several days after the infection begins and has been detected by the innate immune system. Most of the lymphocytes generated by the clonal expansion in any given immune response will eventually die. However, a sig­nificant number of activated antigen-specific B cells and T cells persist after antigen has been eliminated. These cells are known as memory cells and form the basis of immunological memory. They can be reactivated much more quickly than naive lymphocytes, which ensures a more rapid and effec­tive response on a second encounter with a pathogen and thereby usually provides lasting protective immunity.

14
Q

What are the components of the structure of antibodies?

A
  • 2 identical heavy chains and 2 identical light chains, connected by S-S bonds, which makes flexible hinge region that can spread its “arms” out for better binding ability
  • variable and constant regions
    • variable regions contain the binding sites for epitopes
15
Q

If you split an antibody into 3 parts, what are they?

A

The two “arms” are Fab (fragment: antigen binding)

  • retain their antigen binding ability

The “tail” is Fc (fragment: crystallizable)

  • Fc-receptor binding
  • induces complement activation via the classical pathway
16
Q

What is the difference between a linear and discontinuous epitope?

A

Linear epitopes of an antigen have molecules that are next to each other which are recognized by an antibody, but discontinuous epitopes may have molecules that are further apart yet still recognized by the antibody

17
Q

What are the 2 mechanisms for antigen receptor diversity?

A
  • Combinatorial diversity: V(D)J recombination
    • by Rag-1 and Rag-2 proteins: V(D)J recombinase
    • Random assembly of 50 V H , 25 D H , and 6 J H gene segments
      • Antibody V region diversity is greater than that
  • Junctional diversity (addition/removal of nucleotides)

5 x 1013 total receptor diversity

18
Q

What should you know about the antibody isotype IgG?

A
  • monomer
  • four subtypes
  • high concentration in the plasma
  • opsonization, complement activation, phagocytosis
19
Q

What should you know about the antibody isotype IgD?

A

monomer, only traces can be found in the plasma. no secreted form

20
Q

What should you know about the antibody isotype IgE?

A
  • defense against parasitic worms
  • immediate hypersensitivity - Mast cell activation
21
Q

What should you know about the antibody isotype IgA?

A
  • dimer form
  • mucosal immunity
22
Q

What should you know about the antibody isotype IgM?

A
  • pentamer (much larger than the others)
  • in plasma
  • naive B cell antigen receptor, complement activation
23
Q

What are the effector functions of antibodies?

A
  1. ) Neutralization
  2. ) Opsonization
  3. ) Complement activation
24
Q

What type of receptor do B cells use for signaling to activate other B cells?

What important transcription factor is produced?

A

ITAM (immunoreceptor tyrosine-based activation motif)

  • has no tyrosine kinase activity
  • more similar to a Gq GPCR

Transcription factor: NF-kB

25
Q

What are thymus-dependent antigens?

A

Antigens that require T helper cells (CD4+) in order for B cells to respond to them

Others may be thymus-independent, and B cells just begin differentiating into plasma cells w/o help

26
Q

What is the difference between immature and mature B cells, as far as their expression of IgM and IgD receptors goes?

A

Immature B cells express IgM B cell receptors

Mature cells express IgM and IgD (but is still resting until it is activated)