B Cell Development and Immunity

Question 1

Where is hematopoiesis in the fetus?

Answer 1

developing liver

Question 2

Where the primary site of hematopoiesis in adults?

Answer 2

bone marrow

Question 3

How long can naive B cells circulate before apoptosis if they don’t encounter Ag?

Answer 3

2-3 days

Question 4

What gene is expressed during heavy and light chain rearrangement?

Answer 4

RAG

Question 5

When is TdT expressed?

Answer 5

From heavy chain rearrangment to light chain arrangment, but begins going away as light chain since no N regions are added

Question 6

When are surrogate light chain genes expressed?

Answer 6

Only in heavy chain rearrangment region

Question 7

What is receptor editing?

Answer 7

Immature B cells in the BM that are self-reactive will edit the light chain to try to eliminate self-reactivity, if it fails, self-reactive B cell retained in BM

Question 8

What happens to a B cell that see Ag in an early stage without T cell help?

Answer 8

anergy

Question 9

Can B cells recognize Ag presented on dendritic cells?

Answer 9

No, they must see ag in native conformation

Question 10

What is an immune synapse?

Answer 10

Ag-activated B cells act as APC to T cells, induces immunological memory

Question 11

What type of antigen is LPS?

Answer 11

T-independent 1 (TI-1)

Question 12

What type of antigen is bacterial DNA?

Answer 12

TI-1 antigen that can activate B cells specific for bacterial surface Ag

Question 13

How are T-independent responses different from T-dependent responses?

Answer 13

no memory, no IgG response, mainly IgM, short-lived

Question 14

What are TI-1 antigens? What signal replaces T cell signal? What is activated?

Answer 14

LPS, bacterial DNA

• TLR-4 replaces T cell signals
• activates nonspecific B cells to produce IgM against bacterial surface

Question 15

What are TI-2 antigens?

Answer 15

repeating polysaccharides with same epitope that causes crosslinking of receptors to activate

Question 16

In what organ is the highest concentration of B cell development? what regions?

Answer 16

lymph nodes, in the medullary cords and germinal center

Question 17

What is different about follicular dendritic cells? Where are they found? What is their purpose?

Answer 17

don’t process Ag, found in germinal centers, present Ag to B cells

Question 18

Where is a focal point for B cells to undergo cell division, class switching and affinity maturation?

Answer 18

germinal centers

Question 19

What causes hyperIgM syndrome?

Answer 19

lack of CD40 because of lack of T cells, no class switching, no germinal centers

Question 20

What is a centrocyte?

Answer 20

dividing B cell in germinal center

Question 21

What will IL-10 induce a B cell to differentiate into?

Answer 21

plasma cell

Question 22

What will IL-4 cause a B cell to differentiate into?

Answer 22

memory B cell