B-Cell Immunity

Question 1

What are the 3 kinds of B-cells?

Answer 1

1) B-1 cells
2) Conventional B-2 cells
3) Marginal zone B-cells

Question 2

Which type of B-cell requires T-cell help?

Answer 2

B-2 cells require help, and marginal zone B-cells sometimes require help. B-1 cells do NOT require help.

Question 3

Which type of B-cell develops memory?

Answer 3

B-2 cells develop memory, while B-1 cels develop little or none.

Question 4

Where are the different types of B-cells found?

Answer 4

• B-1: body cavities (peritoneal, pleural)
• B-2: secondary lymphoid organs (periphery)
• marginal zone: spleen

Question 5

Which biological molecules are the most immunogenic?

Answer 5

carbs and proteins

Question 6

Which biological molecules are the least immunogenic?

Answer 6

nucleic acids (lipids are also not very immunogenic due to floppy structure)

Question 7

What is an adjuvant, and what is the most common one?

Answer 7

• a substance formulated as part of a vaccine to enhance its ability to protect against infection, often by recruiting/activating APCs
• most common one is Alum (aluminum hydroxide)

Question 8

What are some factors that confer higher immunogenicity?

Answer 8

• large size
• subcutaneous injection
• complex/heterogeneous composition
• slow release adjuvant
• form=denatured and particulate

Question 9

In order for T-cells to help B-cells, they must recognize the same ______ but not the same ______.

Answer 9

antigen; epitope

Question 10

What are thymus-dependent vs. thymus-independent antigens?

Answer 10

• thymus-dependent: an immunogen that

- thymus-independent: an immunogen that requires T-cell cooperation w/ B-cells to result in Ab production

Question 11

Activation of B-cells require 2 signals:

Answer 11

1) Antigen uptake by BCR (immunoglobulin)

2) CD40/CD40L interaction to induce cytokines from helper T-cell, which in turn activate the B-cell

Question 12

B-cells recognize the _________, while T-cells recognize the _______. (in regard to the antigen)

Answer 12

native polypeptide; processed antigen

Question 13

Which class of antibody dominates during the primary vs. secondary response?

Answer 13

• primary: mostly IgM (low-affinity)

- secondary: mostly IgG (high-affinity)

Question 14

Which enzyme responsible for isotype switching?

Answer 14

AID (activation-induced cytidine deaminase)

Question 15

At which point of the antibody response does class switching typically happen?

Answer 15

at the end of the primary response; shows up during the secondary response

Question 16

During isotype switching, which genes must come together?

Answer 16

switch genes for the isotypes that are to be switched (Sμ and Sγ for IgM–>IgG, Sμ and Sα for IgM–>IgA, etc.)

Question 17

What are the 3 key events that happen in the germinal center?

Answer 17

1) Somatic hypermutation
2) Class switch recombination
3) Development of memory B-cells and plasma cells

Question 18

Describe the light zone vs. dark zone of the germinal center.

Answer 18

• light zone: contains follicular T-cells and DCs; where selection of B-cells occurs
• dark zone: contains actively proliferating B-cells undergoing somatic hypermutation and class switching

Question 19

Is somatic hypermutation random or non-random? What is the implication of this?

Answer 19

It is random, which means we could end up with non-functional or self-reactive B-cells after hypermutation occurs.

Question 20

Which type of B-cells respond to carbohydrate antigen?

Answer 20

B-1 and marginal zone B-cells

Question 21

What are some characteristics of the antibody response to a T-independent antigen?

Answer 21

• no germinal center formation
• no somatic hypermutation
• usually no memory
• no isotype switch

Question 22

Which is the T-independent B-cell?

Answer 22

B-1 cells

Question 23

When does a B-cell follicle and germinal center form?

Answer 23

After a B-cell is fully activated by (1) binding antigen to BCR and (2) receiving T-cell help via interaction b/t CD40/CD40L and subsequent cytokine production by T-cell.