#5 - Life of a B Cell: Surveillance and Warfare

Question 1

what is a naive or virgin B cell?

Answer 1

a B cell that has not seen its antigen

Question 2

what’s the circuit time for a B cell?

Answer 2

12-24 hours

Question 3

how many WBC in the blood (per microliter)?

Answer 3

4k - 11k

Question 4

how many lymphocytes (per microliter)

Answer 4

1k-4k (15-40%)

Question 5

what is the normal ratio of T cells to B cells?

Answer 5

2:1

Question 6

what is the composition of the thoracic lymph duct?

Answer 6

effector T cells and memory and plasma B cells, but few naive cells

Question 7

how do naive cells enter the lymph nodes?

Answer 7

via the HEV by expressing L-selectin (CD62L) and interacting with GlyCAM

Question 8

how do effector cells get targeted to their destination? what are the specific addressin combinations?

Answer 8

VCAM-VLA4, ICAM-LFA1, CD:LFA3 (in that order of importance) (CLA in skin, a4b7 in gut)

Question 9

what’s the difference between primary and secondary follicles?

Answer 9

primary follicles don’t have germinal centers

Question 10

what type of cells preferentially reside in the marginal and sub-capsular sinuses?

Answer 10

memory B cells (also dendritic cells)

Question 11

what are the two steps for B cell activation, broadly speaking? is there a third step?

Answer 11

antigen presentation to the antigen on the cell surface and T helper cell binding. Cytokines act as a sort of third step

Question 12

what is linked recognition?

Answer 12

T cell and B cell rendevous

Question 13

after antigen is presented to the antibody what happens to the B cell?

Answer 13

it expresses MHC type II with the relevant derived proteins
CD40 is upregulated
CD80/86 are upregulated

Question 14

from which type of cells do most T cells get activated? what other type of cells can activate T cells?

Answer 14

dendritic cells, B cells

Question 15

what happens in the dark zone?

Answer 15

massive clonal expansion and somatic mutation

Question 16

which chains of the antibodies are mutated in somatic hypermutation?

Answer 16

both heavy and light

Question 17

what is the key enzyme for somatic mutation?

Answer 17

AID

Question 18

what happens in the light zone?

Answer 18

FDC’s direct survival of the fittest and class switching

Question 19

what are these processes (the dark zone and light zone processes together) called?

Answer 19

affinity maturation

Question 20

where are the main places for plasma cells?

Answer 20

bone marrow (longest lived (IL=6)), splenic red pulp, medullary cords of lymph nodes

Question 21

what type of Ig do memory cells lack?

Answer 21

IgD

Question 22

what regulates class switching?

Answer 22

T cells

Question 23

which chains are modified?

Answer 23

just the heavy chain

Question 24

what type of cytokine results in IgA?

Answer 24

TGF beta (Treg); IL-5 (Th2)

Question 25

what type of cytokine results in IgG4, IgE

Answer 25

IL-4, IL-13 (Th2)

Question 26

what type of cytokine results in IgG1

Answer 26

IFN-gamma (Th1)

Question 27

CTLA-4 Ig does what?

Answer 27

blocks the CD28 - CD80/86 interactions (in other words, the same thing as CTLA-4)

Question 28

what disease does mutations in CD40L result in?

Answer 28

Hyper-IgM

Question 29

what disease does mutations in AID lead to?

Answer 29

Hyper-IgM

Question 30

what disease does mutation in ICOSL and/or ICOS lead to?

Answer 30

Common Variable Immunodeficieny (no class-switched antibodies)

Question 31

what type of cell leads to acute lymphoblastic leukemia?

Answer 31

Pre-B

Question 32

what type of cell leads to chronic lymphocytic leukemia?

Answer 32

mature B cell

Question 33

what type of cell leads to diffuse large cell lymphoma?

Answer 33

germinal center B cells

Question 34

what type of cell leads to multiple myeloma?

Answer 34

plasma cell