B Cells & Their Response to Antigens (13)

Question 1

B cells differentiate to _____ cells which then secrete _______

Answer 1

plasma cells
antibodies

Question 2

Antibodies are also called _____. What is their structure?

Answer 2

immunoglobins
glycoproteins with a common basic structure

Question 3

What are membrane-bound Igs also called?

Answer 3

B cell receptors

Question 4

A B cell has ______ in its membrane. It has around 300,000 copies of _____ BCRs

Answer 4

B cell receptors
IDENTICAL

Question 5

What is a BCR?

Answer 5

a sample of antibody the B cell and its clones will produce

Question 6

One B cell can recognize one ______

Answer 6

epitope

Question 7

If a B cell is activated, what happens?

Answer 7

expands clonaly
some of the clones differentiate into plasma cells (which secrete the antibody) and then become long-lived memory cells

Question 8

What are plasma cells?

Answer 8

cells that secrete antibody
derived from B cells

Question 9

What is the structure of an immunoglobin molecule?

Answer 9

glycoprotein with 4 chains that make Y-shaped molecule
hinge region for flexibility

Question 10

What part of the B cell is “hyper-variable”?

Answer 10

complementarity-determining regions

Question 11

What forms the antigen-binding site of the B cell?

Answer 11

complementarity-determining region

Question 12

What is framework versus complementarity-determining regions?

Answer 12

complementarity: binds to antigen, “hyper-variable”
framework region: region of antibody that surrounds and provides structural support to CDRs

Question 13

When the immunoglobin (BCR) is membrane-bound on B cell, which protein is there that induces signal transduction?

Answer 13

CD79

Question 14

What is the first antibody made?

Answer 14

IgM
shows early signs of infection

Question 15

What is class/isotype switching? When does it only happen?

Answer 15

changing antibody isotypes
only when B cells have help from T helper cells

Question 16

What helps B cells respond to an antigen?

Answer 16

helper T-cells contact
complement
interaction of PAMPs and PRRs
cytokines (produced by helper T cells)

Question 17

What protein is important for macrophages?

Answer 17

CD40 and CD154

Question 18

T/F: In an secondary immune response, only dendritic cells help

Answer 18

FALSE - primary!

Question 19

What is CD40 & CD154 mediated dialog?

Answer 19

B: used in proliferation
B: Ig production
B: Ig class switching
dendritic: antigen presentation
dendritic: cytokine production
dendritic: cell survival
macrophage: cytokine production

Question 20

What is the role of innate immune signals in B cell activation?

Answer 20

Question 21

What does TLR bind to? It is a PRR (pattern-recognition receptor)

Answer 21

binds to PAMPs on pathogen

Question 22

Which antibody response, primary or secondary, is larger?

Answer 22

secondary

Question 23

What is the relative antibody in primary response?

Answer 23

usually IgM

Question 24

What is the relative antibody in secondary response?

Answer 24

relative increase in IgG and under certain situations in IgA or IgE (heavy-chain isotype switching)

Question 25

Primary response has a [high/low] average affinity and secondary response has a [high/low] average affinity

Answer 25

Primary: low, more variable
Secondary: higher, affinity maturation

Question 26

B cells with high-affinity Ig bind antigen on _____ and present antigen to helper T cells

Answer 26

follicular dendritic cells (FDCs)

Question 27

T/F: B cells that recognize antigen on follicular dendritic cells or interact with helper T cells are selected to survive

Answer 27

TRUE

Question 28

IgE is immunity against ____ and plays a role in immediate hypersensitivity, or ______

Answer 28

all helminths
mast cell degranulation

Question 29

What is IgA?

Answer 29

for mucosal immunity (transport of IgA through epithelia)

Question 30

What is the difference between T-dependent and T-independent antibody response?

Answer 30

T-dependent: surge of IgG secondarily, memory, IgM —> IgG
T-INdependent: no class switch, no memory

Question 31

When BCRs are shed into body fluid, they are called _____

Answer 31

immunoglobins or antibodies

Question 32

BCRs consist of 2 ____ and 2 ______ bound together by disulfide bonds

Answer 32

2 heavy chains
2 light chains

Question 33

Activated B cells become either antibody producing _____ or ______

Answer 33

plasma cells
memory cells

Question 34

Where does the differentiation of B cells into plasma cells take place?

Answer 34

in the germinal centers of lymph nodes and other secondary lymphoid organs