#5 - Life of a B Cell: Surveillance and Warfare Flashcards
what is a naive or virgin B cell?
a B cell that has not seen its antigen
what’s the circuit time for a B cell?
12-24 hours
how many WBC in the blood (per microliter)?
4k - 11k
how many lymphocytes (per microliter)
1k-4k (15-40%)
what is the normal ratio of T cells to B cells?
2:1
what is the composition of the thoracic lymph duct?
effector T cells and memory and plasma B cells, but few naive cells
how do naive cells enter the lymph nodes?
via the HEV by expressing L-selectin (CD62L) and interacting with GlyCAM
how do effector cells get targeted to their destination? what are the specific addressin combinations?
VCAM-VLA4, ICAM-LFA1, CD:LFA3 (in that order of importance) (CLA in skin, a4b7 in gut)
what’s the difference between primary and secondary follicles?
primary follicles don’t have germinal centers
what type of cells preferentially reside in the marginal and sub-capsular sinuses?
memory B cells (also dendritic cells)
what are the two steps for B cell activation, broadly speaking? is there a third step?
antigen presentation to the antigen on the cell surface and T helper cell binding. Cytokines act as a sort of third step
what is linked recognition?
T cell and B cell rendevous
after antigen is presented to the antibody what happens to the B cell?
it expresses MHC type II with the relevant derived proteins
CD40 is upregulated
CD80/86 are upregulated
from which type of cells do most T cells get activated? what other type of cells can activate T cells?
dendritic cells, B cells
what happens in the dark zone?
massive clonal expansion and somatic mutation
which chains of the antibodies are mutated in somatic hypermutation?
both heavy and light
what is the key enzyme for somatic mutation?
AID
what happens in the light zone?
FDC’s direct survival of the fittest and class switching
what are these processes (the dark zone and light zone processes together) called?
affinity maturation
where are the main places for plasma cells?
bone marrow (longest lived (IL=6)), splenic red pulp, medullary cords of lymph nodes
what type of Ig do memory cells lack?
IgD
what regulates class switching?
T cells
which chains are modified?
just the heavy chain
what type of cytokine results in IgA?
TGF beta (Treg); IL-5 (Th2)
what type of cytokine results in IgG4, IgE
IL-4, IL-13 (Th2)
what type of cytokine results in IgG1
IFN-gamma (Th1)
CTLA-4 Ig does what?
blocks the CD28 - CD80/86 interactions (in other words, the same thing as CTLA-4)
what disease does mutations in CD40L result in?
Hyper-IgM
what disease does mutations in AID lead to?
Hyper-IgM
what disease does mutation in ICOSL and/or ICOS lead to?
Common Variable Immunodeficieny (no class-switched antibodies)
what type of cell leads to acute lymphoblastic leukemia?
Pre-B
what type of cell leads to chronic lymphocytic leukemia?
mature B cell
what type of cell leads to diffuse large cell lymphoma?
germinal center B cells
what type of cell leads to multiple myeloma?
plasma cell
