Immunology Lecture 10. Flashcards Preview

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Flashcards in Immunology Lecture 10. Deck (31):
1

What is the life cycle of a B cell?

1. generation of diverse and clonal expressed B-cell receptors in bone marrow 2. alteration, elimation, or inactivation of B cell receptors that bind to self (negative selection) 3. promotion of a fraction of immature B cells to become mature B cells in secondary lymphoid tissues (positive selection - not important like with T cells) 4. recirculation of mature B cells between lymph, blood, and secondary lymphoid tissues 5. activation and clonal expansion 6. differentiation to antibody-secreting plasma cells

2

Where do B cells develop?

bone marrow

3

What stage do B cells exit the bone marrow?

mature naive B cells (have not yet seen antigen)

4

What do B and T cells develop from?

pluripotent progenitor cells

5

CD34

marker for pluripotent hematopoietic stem cell

6

What is the immunoglobulin status of an immature B cell?

a heavy and light chain. IgM on surface

7

What does a pre-BCR do?

signals that a functional receptor has been made (from heavy chain - no light chain made yet)

8

What is the importance of allelic exclusion with B cells?

gives homogeneous B-cell receptors with high-avidity binding

9

What are most B cell light chains?

kappa (as opposed to lambda) because kappa chain always made first

10

What are the two checkpoints in B cell development?

pre-B cell receptor - (selects for functional heavy chains) AND B-cell receptor (selects for functional light chains)

11

TdT

adds diversity in junctional regions (N nucleotide addition)

12

Burkitt’s Lymphoma

caused by a chromosomal aberration during B cell development - oncogenic effect

13

What is the difference between a B1 cell and a B2 cell?

B1 produced by a fetus, more primitive, less developmental steps (more IgM) - self renewing, no need for T cell help

14

What happens when a B cell reacts with self antigen?

immature B cell is retained in bone marrow where it goes through receptor editing (or dies)

15

What happens when B cells binds to self antigen in periphery?

signaled to make IgD and become unresponsive to antigen, does not survive for long

16

Where do B cells make final maturation?

periphery

17

What is the main purpose of lymph nodes?

bring immune cells together

18

What is a germinal center?

where maturation of B cells into high affinity happens (also plasma cells and memory cells) - intense competition for limiting antigen (somatic hypermutation)

19

What stage in development does Hodgkin’s lymphoma arrise from?

germinal center B cell

20

What stage in development does multiple myeloma arrise from?

plasma cell (hybridoma - monoclonal antibody)

21

What is the order of development with B cells?

stem cell —> pro-B cell —> pre-B cell —> immature B cell —> mature naive B cell—> antigen activated lymphoblast (isotype switching) —> antibody-secreting plasma cell —> memory cell

22

What happens to a B cell in the periphery?

naive lymphocytes arrive at lymph nodes in arterial blood, lymphocytes and lymph return to blood via lymphatics, venous blood returns to heart (pathogens from site of infection reach lymph nodes via lymphatics) - die if they don’t encounter antigen

23

What defines B cells?

CD19

24

How do B cells signal?

cross-linking of B cell receptors by antigen, phosphorylation, signaling cascade begins that creates activating signals

25

Under what circumstance is T cell help not needed in B cell activation?

extensive cross-linking

26

CD40

on B cell - CD40L on T cell activates, also causes release of IL-4,5,6 which cause B cell proliferation, resting memory cells, and plasma cells

27

IL-4

induces IgG and IgE

28

IL-5

augments production of IgA

29

What happens in medullary cords of lymph nodes?

IgM response

30

What is the main property of plasma cells?

just Ig secretion - don’t switch, don’t grow - factories

31

Isotype of antibody produced by memory B cell?

IgG, IgA (higher affinity and somatic hypermutation)