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Term III: Immunology > B Cells & Antibodies > Flashcards

B Cells & Antibodies Flashcards

1
Q

What chromosome are the gene segments that make up the final heavy chain (Hc) gene located on?

A

Chromosome 14

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2
Q

What are the four separate gene segments that make up the finished heavy chain protein?

A

V, D, J, and C

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3
Q

What do we call the antigens that match the B-cell receptor (BCR)? What do we call the region of this antigen that binds BCR? How many AA’s is it usually?

A

Cognate

Epitope - 6 to 12 AAs

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4
Q

Which immune system decides whether an invasion is dangerous - innate or adaptive?

A

Innate

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5
Q

What is a B cell called if it has never encountered its cognate antigen? What if they have encountered their cognate?

A

Naive or virgin

Experience

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6
Q

What are the two ways naive B cells can be activated?

A
  1. W/ assistance of helper T cells (T-cell dependent activation)
  2. T-cell independent activation
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7
Q

What two signals does activation of naive B cells require?

A
  1. Clustering BCR’s w/ cross-linking + co-stimulatory signal

2. T-cell dependent activation signaling supplied by helper T cell

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8
Q

What is the surface protein on helper T cells that binds to B-cells and sends co-stimulatory signal to activate B cell?

A

CD40L

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9
Q

What is the only type of antigen Th cells recognize?

A

Protein antigens

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10
Q

What is the third, unusual/abnormal way BCRS can be activated?

A

Mitogen binds to molecules on B cell surfaces that are NOT BCRs and clusters them - this is polyclonal activation that does not depend on cognate Ag

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11
Q

What are the three steps of B cell maturation? Is this order-dependent?

A
  1. Class switching
  2. Somatic hypermutation
  3. Career decision

Not order dependent

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12
Q

What types of antibody does a virgin B cell produce when first activated?

A

IgM antibodies (the default)

also IgD, but only a small fraction

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13
Q

What region of the antibody determines its class?

A

Fc (constant) region

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14
Q

What Ab class is very good at activating complement cascade? How does it do this?

A

IgM - it binds C1 complexes formed by complement on its Fc region, bringing them close together, which forces inhibitors to fall off and initiates the cascade that produces C3 convertase

IgG also binds C1 to its Fc region, but only one copy (so you need a lot of IgG around)

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15
Q

What IgG subclass fixes complement the best? What types of cells have receptors for this subclass’s Fc region?

A

IgG3 - Natural killer cells

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16
Q

What IgG sublcass is good at opsonizing invaders for macrophage ingestion?

A

IgG1

17
Q

What is another name for IgG antibodies?

A

Gamma globulins

18
Q

What is the most abundant Ab class in the human body?

A

IgA - guards mucosal surfaces (digestive, respiratory, & reproductive)

(IgG is most abundant in the blood)

19
Q

What Ab class is structured like two molecules held together with a clip?

A

IgA

20
Q

What Ab class is structured like 5 IgG antibodies put together and is massive?

A

IgM

21
Q

What Ab class is good at collecting pathogens into clumps large enough to be cleared with mucus and feces? Can it also fix complement?

A

IgA - cannot fix complement

22
Q

What Ab class is secreted into milk of nursing mothers?

A

IgA

23
Q

What Ab class can pass across placenta to fetus?

A

IgG

24
Q

Degranulation of what cell causes anaphylactic shock?

A

Mast cells (tissue basophils)

25
Q

What Ab class is produced in large amts in response to allergen exposure?

A

IgE

26
Q

If an area is rich in cytokines IL-4 and 5, what class do Abs switch to?

A

IgE (good for parasites)

27
Q

If an area is rich in IFN-alpha cytokines, what class do B cells produce?

A

IgG3 (good for bac. and viruses)

28
Q

If an area is rich in TGF-beta cytokines, what class do B cells produce?

A

IgA (good for viruses)

29
Q

What types of cells secrete cytokines that direct Ab class switching and somatic hypermutation?

A

T-helper cells

30
Q

What region of the Ab does somatic hypermutation mutate?

A

Fab - Antigen binding region

31
Q

What is T-cell independent B cell activation usually a response to? Does it undergo class switching? Somatic hypermutation?

A

Carbohydrates on bacterial surfaces

No class switching, no somatic hypermutation

32
Q

Through what process does a B cell change its constant, Fc region? Its antigen binding region, Fab?

A

Fc - class switching

Fab - somatic hypermutation

33
Q

What are the two fates of B cells?

A

Plasma cells - antibody factories

Memory cells

Term III: Immunology (15 decks)

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