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Immunology > B Cell Activation (Exam 2) > Flashcards

B Cell Activation (Exam 2) Flashcards

1
Q

What are the 3 phases of the humoral immune response?

A
  1. recognition phase
  2. proliferation phase
  3. differentiation phase
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2
Q

In the recognition phase of humoral immune response, ________ recognize antigen and become activated.

A

B cells

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3
Q

In the proliferation phase of humoral immune response, activated B cells undergo __________.

A

clonal expansion

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4
Q

In the differentiation phase of humoral immune response, progeny B cells develop into effector cells as either _______ or ______.

A

plasma cells
memory B cells

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5
Q

_________ antigen require help of CD4+ T cells for recognition while _______ does can formulate a responses without T cell help.

A

thymus-dependent
thymus-independent

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6
Q

What types of antigen is thymus independent? Dependent?

A

Independent: polysaccharides, lipid, nucleic acid antigen

Dependent: protein antigen

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7
Q

What cell type mediates thymus-dependent antigen?

A

follicular B cells

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8
Q

Thymus-independent antigen is mediated by ________ cells in secondary lymphoid tissue and ________ cells in mucosal sites/peritoneum.

A

marginal zone B cells
B1 cells

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9
Q

What 3 anatomic compartments are humoral immune responses initiated in?

A
  1. spleen
  2. lymph nodes
  3. mucosal lymphoid tissue
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10
Q

What is class switching?

A

process where activated B cells begin producing antibodies other than IgM (such as IgA, IgG, IgE)

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11
Q

Term for process where overtime, B cells produce higher affinity antibodies that are selected for.

A

affinity maturation

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12
Q

Which antibodies are secreted in the primary antibody response vs. secondary antibody response?

A

primary: IgM
secondary: class-switch antibodies (IgA, IgG, IgE)

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13
Q

Which antibody isotypes serve as antigen receptors on the surface of naive B cells?

A

IgM + IgD

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14
Q

What does ITAM stand for?

A

immunoreceptor tyrosine-based activation motif

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15
Q

What does ITAM do?

A

motif on B cell receptor which helps initiate a signaling cascade to activate the cell

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16
Q

ITAM recruits _______ to cause a conformational change which allows for a signaling cascade which activates B cells.

A

tyrosine kinase

17
Q

What are two invariant molecules? What special structure is associated with them?

A

Ig(alpha) + Ig
ITAM

18
Q

What do helper T cells help B cells to do?

A

produce signals to stimulate B cell responses (such as formation into plasma cells and B memory cells)

19
Q

Where do early events in T-cell dependent B cell activation occur?

A

just outside follicle at extrafollicular locus

20
Q

Within a follicle of a secondary lymphoid organ, _________ is a B cell zone which produces high quality antibodies and B cells undergo proliferation.

A

germinal center

21
Q

In helper T cell-mediated B cell activation, B cells bind to antigen and become activated. This leads to an upregulation of ________. What is the purpose?

A

costimulators (B7)
better able to activate T cells

22
Q

What two structures do T cells recognize in T cell-mediated B cell activation and allows them to respond?

A

MHC-peptide complex + costimulators

23
Q

When T cells recognize MHC-peptide complex and costimulators, they express ______ ligand which stimulates them to secrete _________.

A

CD40
cytokines

24
Q

CD40 binding to B cells causes what response? Cytokines from T cells stimulate B cells to do what?

A

CD40 –> B cell proliferation
Cytokines –> germinal center (high quality antibody production)

25
Q

(T/F) The initial interaction between B and CD4 T cells outside of the secondary lymphoid organ follicle can induce some isotype switching.

A

True

26
Q

Where does most isotype switching occur?

A

germinal center

27
Q

Term for randomized mutation which leads to B cells with high affinity antibodies which will survive when others will die by apoptosis.

A

somatic hypermutation

28
Q

What is B7?

A

costimulatory molecule upregulated in T cell-mediated B cell activated so B cells can better activate T cells

29
Q

_______ is a protein on cell membrane which binds to B cell receptors to stimulate their proliferation and differentiation which leads to a germinal center reaction.

A

CD40

30
Q

What are the 4 antibody subclasses?

A

IgG
IgA
IgM
IgE

31
Q

Match the effector functions to the appropriate antibody isotype:

  1. helminth immunity | mast cell degranulation
  2. mucosal immunity
  3. complement activation
  4. opsonization, phagocytosis, complement activation, neonatal immunity
A
  1. IgE
  2. IgA
  3. IgM
  4. IgG
32
Q

Each cytokine can influence class switching. Match which antibody isotype is stimulated by each:

  1. no cytokine signal
  2. IFN-y
  3. IL-4
  4. TGF-B
  5. IL-5
A
  1. IgM
  2. IgG2a
  3. IgG1; some IgE
    4/5. IgA
33
Q

Follicular dendritic cells express high levels of ______ and ______ receptors which bind to complement or antibodies.

A

Fc
complement

34
Q

What is the main function of IgM?

A

complement activation

35
Q

Explain antibody feedback.

A

IgG has regulatory or inhibitory role on B cell response to antigen (to keep response in check)

36
Q

________ is an inhibitory receptor on antigen-specific B cell which inhibits B cell activation.

A

Fc-y RII

37
Q

Fcy RII receptor can inhibit B cell response because it has _______.

A

ITIM (immunoreceptor tyrosine-based inhibition motif)

38
Q

When Fc-y RII receptor is engaged, it (phosphorylates/dephosphorylates) ITIM which forms a “docking site” called _______ which (phosphorylates/dephosphorylates) to inhibit the signaling pathway, and therefore, B cell activation is inhibited.

A

phosphorylates
SHIP
dephosphorylates

39
Q

How does the circulating level of secreted IgM and IgG modulate the antibody repsonse?

A

high IgM at beginning –> upregulating response

high IgG later –> downregulating response

Immunology (17 decks)

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