Lecture 9 - B cell response/antibodies Flashcards

1
Q

Humoral immunity

A

antibody-mediated

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2
Q

why does the plasma cells have more space

A

needs for endoplasmic reticulum and antibody synthesis

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3
Q

If immature B cells do not find an antigen they

A

leave the bone marrow

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4
Q

if BCR binds to self-antigen they

A

are eliminated via apoptosis or undergo receptor editing

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5
Q

If a B cell is still reactive to self antigens following receptor editing they

A

undergo apoptosis

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6
Q

Central tolerance of B cells refers to

A

The double-positive system before leaving the bone marrow

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7
Q

Transitional B cells are

A

B cells that have exited the bone marrow into circulation

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8
Q

Peripheral tolerance of B cells refers to

A

Single positive system of B cells maturation in the spleen

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9
Q

Transitional B cells with no strong self reaction

A

mature

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10
Q

what is the final stage of B cell maturation

A

upregulation of surface IgD

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11
Q

summarize the stages of B cell development

A

1 - stem cell in bone marrow
2 - pre B cell in lymphoid organs
3 - immature B cell obtain membrane IgM and IgD
4 - mature B cell in secondary organs obtain antigen
5 - plasma cells secrete immunoglobulins

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12
Q

T/F: other species have peyer’s patches but they are not the primary organ like in pigs

A

True

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13
Q

Fc receptors bind to

A

the B cell membrane

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14
Q

complement receptors do what

A

regulate

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15
Q

cytokine receptors do what

A

co-stimulate and regulate

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16
Q

BCRs consist of

A

immunoglobin domains

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17
Q

what domain of the BCR is the antigen-binding site

A

light chains

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18
Q

what are the signal transduction components of BCR

A

CD79 alpha and beta

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19
Q

how are BCRs and TCRs similar

A

antigen-specific
respond to epitomes presented in the linear form

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20
Q

How are BCRs different from TCRs

A

recognize free-floating native (3D) antigen, giving them more binding variety

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21
Q

Summarize activation of helper T cells via B cells

A

1 - antigen binds to BCR and is ingested
2 - antigen is bound to MHC II
3 - MHC II is presented on the membrane to TCRs

22
Q

where are antigens presented to B cells

A

lymph nodes

23
Q

How are B cells activated

A

dendritic cells present linear antigens or unprocessed native (3D) bind

24
Q

summarize T cell-independent B cell activation

A

1 -polyvalent antigen binds to multiple BCR
2 - production of IgM (low affinity)

25
Q

Summarize cross-links

A

1 - native antigen endocytosed
2 - expressed by B cell MHC II (exposure tp PAMPs and complements upregulate stimulatory molecules)
3 - processed epitopes to CD4+ T cells
4 - TCR binding induces CD154 expression
5a - CD154 binds to CD40 on B cell promoting immunoglobulin synthesis and proliferation
5b - CD40 promotes CD86 expression on B cells
6 - CD86 binds CD28 on T cell
7 - IL4 cytokine production

26
Q

what does IL4 cytokine production give as an effect of cross-links

A

B cells differentiate

27
Q

what mediates class switching of IgM to another immunoglobin

A

cytokines

28
Q

T/F: B cell immunoglobins are controlled by T cells

A

True

29
Q

what determines an immunoglobins isotype

A

1/5 heavy chains

30
Q

Immunoglobin structure

A

2 heavy and 2 light chains

31
Q

What immunoglobins lack a hinge region? what do they have instead?

A

IgM and IgE; extra heavy chain

32
Q

IgM

A

immature b cells and antigen-specific BCR
primary immune response
can activate complement

33
Q

IgG

A

B cells in secondary response
can activate complement

34
Q

IgA

A

mucosal surfaces, secreted by MALT
secretory component
CANNOT activate complement

35
Q

IgD

A

immature B cells; function unclear

36
Q

IgE

A

immunity to parasitic worms and allergies
forms cross-links
CANNOT activate complement

37
Q

Fc fragments mediate what functions

A
  • complement activation
  • opsonization
  • cellular activation
38
Q

What are the 5 biological functions of antibodies

A
  1. neutralization of microbial actions/toxins
  2. opsonization
  3. NK kills antibody-bound cells
  4. lysis of abnormal cells
  5. IgE activation of mast/eosinophils
39
Q

what part of the antibody is variable

A

antigen-binding site

40
Q

VDJ

A

heavy chain

41
Q

VJ

A

light chain

42
Q

What recombination occurs in terminal differentiation

A

light chain rearrangement

43
Q

Summarize affinity maturation

A
  • B cells activate
  • mutation initiated by AID, turning cytidine to uridine
  • error-prone DNA polymerase fixes uridine presence introducing further mutations
  • changes arise in variable regions
  • B cell with highest affinity to antigen differentiates to plasma cell
44
Q

What does affinity maturation contribute to

A

improved antigen binding abilities of antibodies

45
Q

What is isotype switching

A

activated B cells switch from producing IgM/IgD to IgG/IgA/IgE

46
Q

Thelper 1 cell induce what isotype

A

IgG

47
Q

Thelper 2 cell induce what isotype

A

IgE

48
Q

Treg cells induce what isotype

A

IgG

49
Q

what does isotype switching improve

A

antibody function in the Fc region

50
Q

B1 cell characteristics

A

less common
spontaneously produce IgM/”natural antibodies”
target lipids/carbohydrates

51
Q

The binding of Fc antibody portions to their receptors can trigger what sorts of actions

A
  1. phagocytosis/killing
  2. degranulation
  3. downregulate inflammation
52
Q

T/F: antibodies are found bound to their Fc receptors

A

False