B Cells

Question 1

CD79 heterodimers

Answer 1

the signal transducers of the BCR. They are formed by the pairing of CD79a (Ig-alpha) and CD79b (Ig-beta). The CD79b chains are identical in all BCRs. the Cd79a chains differ depending on their associated heavy chains and employ different signaling pathways

Question 2

B Cell Antigen Processing

Answer 2

1. antigen bound to a BCR may be ingested and processed
2. the processed antigen can then be presented on MHC class II molecules
3. Because B cells have many identical BCRs, they can bind, process, and present a large amount of each specific antigen

Question 3

B Cell-T Helper Cell Conversion

Answer 3

1. antigen binding to the TCR causes the cell to express CD154
2. CD154 binds to CD40 on the B cell and promotes immunoglobulin synthesis
3. It also promotes CD86 expression on the B cell
4. CD86 binds to CD28 on the T cell and triggers IL-4 production
5. IL-4 promotes B cell growth and differentiation

Question 4

B Cell Stimulation

Answer 4

requires multiple co-stimulatory signals in addition to specific antigen in order to mount a strong antibody response

Question 5

T-Dependent

Answer 5

responses to protein antigens require T cell help. These responses are slower to develop but result in more durable, high-affinity antibodies that are typically of the IgG, IgA, or IgE isotypes

Question 6

T-Independent

Answer 6

polysaccharide antigens can activate B cells without T cell help. These responses are rapid but relatively simple, consisting of mostly low-affinity IgM antibodies

Question 7

Bound complement turning on B cells

Answer 7

it cross-links CD19/21 and draws it close to the BCR. When CD19/21 comes close to the BCR co-stimulation occurs and the B cell response is potentiated

Question 8

Somatic Mutation

Answer 8

B cells are selected based on their affinity for antigen. This occurs in germinal centers.

1. Activation of B cells and migration into germinal center
2. B cell proliferation and somatic hypermutation
3. selection of high affinity B cells; isotype switching
4. exit of high-affinity antibody-secreting cells and memory B cells

Question 9

Plasma Cells

Answer 9

Differentiated B cells. Can generate thousands of immunoglobulin molecules per second. Not usually long-lived. May become cancerous-myelomas