B-cell Immunity

Question 1

Differentiate B-1 cells, B-2 cells and marginal zone B-cells

Answer 1

B-1 cells and MZ B cells are innate-like.

Most adaptive responses are mediated by B-2 cells.

Question 2

What is the role of an adjuvant in a vaccine?

Answer 2

Adjuvants are substances that enhance immunogenicity. Alum is most commonly used - it makes the immunogen particulate and readily ingested by APCs

Too little immunogen results in no immune response

Question 3

Does size affect the immunogenicity of an protein?

Answer 3

Yes- larger proteins increase their immunogenicity

Question 4

How does the dose affect the immunogenicity of a protein?

Answer 4

Too small or too high doses on a protein make it less immunogenic.

Intermediate doses lead to the best immune response

Question 5

Which route of administration leads to the greatest immune response?

Answer 5

Subcutaneous (like intramuscular injections)

Question 6

What form of a protein makes it more immunogenic?

Answer 6

Proteins should be particulate in order to generate a greater immunogenic response (soluble proteins are not taken up by DCs)

Question 7

For T-dependent responses, B cell activation requires what two signals?

Answer 7

1) Interaction of BCR with antigen
2) Interaction of TCR with peptide/MHC complex and interaction between costimulatory molecules CD40 (B cell) and CD40L (T cell)

Question 8

What category of antigens are T-cell independent?

Answer 8

Polysaccharides

Question 9

Name three cytokines released from T cells that, in addition to the expression of CD40L, drives B cells to proliferate and differentiate into plasma cells

Answer 9

IL-4, IL-5, IL-6

Question 10

For T-dependent antigens, do the B and T cell recognize the same epitope?

Answer 10

No- B and T cells must recognize the same ANTIGEN, but not the same epitope

Question 11

What regulates isotype switching in B cells?

Answer 11

T-cell cytokines.

Question 12

Which enzyme is responsible for isotype switching?

Answer 12

AID

Question 13

Where does isotype switching, somatic hypermutation, and development of B cells/memory cells occur?

Answer 13

Germinal centers

Question 14

What happens in the dark zones of germinal centers?

Answer 14

Proliferation, somatic hypermutation

Question 15

What happens in the light zones of germinal centers?

Answer 15

class switching, differentiation, development of memory B cells.

Question 16

Which enzyme is required for somatic hypermutation?

Answer 16

AID- it is also required for class-switching

Question 17

Describe the antibodies formed by T-independent antigens

Answer 17

The antibodies formed are usually IgM and are not somatically mutated. Consequently, the antibodies formed are lower affinity than those of T-dependent antigens. They are, however, important for antibody responses to bacterial polysaccharide antigens.

Question 18

Do T-independent antigens lead to the production of memory cells/

Answer 18

Generally no