Antibody mediated immune response Flashcards
Negative selection of B cells: where does this occur
in the bone marrow before leaving
Negative selection of B cells: another name for this is called ____ and why?
central tolerance, because it occurs in the central lymphoid organs
Negative selection of B cells: what is it
the elimination of B cells with too strong self-recognition
Negative selection two parts
1) self-recognition = apoptosis
2) non-self rec. = receptor editing, Ig gene recombination begins to express new light chain
What does central tolerance lead to
it reactivates gene rearrangement
Ig gene recombination on the BCR, which leads to expressing a new light chain
phases of B cell activation
a) Naive IgM/IgD B cell rec. Ag (like a microbe)
b) Stimulus (cytokines/Helper T Cell inpute) –> Activation
c) Activation of B Lymphocytes = clonal expansion
d) differentiation
Ag-recognition –> Activation via stimulus –> clonal expansion –> differentiation
After differentiation, what are the 4 possible behavioral outcomes of the B lymphocytes
1) effector secretion of IgM
2) IgG expressing –> isotype switching
3) High affinity IgG expression –> affinity maturation (produces strong IgG)
4) High affinity IgG expression –> memory B cell
Where does naive B cell recognition of Ag occur?
in the LN
Activation of B cells in the LN initiates the following processes
1) Ag activated B cell proliferates (mitosis)
2) Activated B cell expresses the following:
i. B7 (CD80/CD86)
ii. increased Ag expression via MHC II
iii. Receptors for cytokines produced by Th cells
3) Secrete low level of IgM
What mechanism helps with the Ag recognition if Ag/microbe/etc is very low in the body?
the complement system
the receptor that is crucial is CR2, specifically, which binds C3b bound to microbe simultaneously as Ag binds to BCR
What aspect of CR2 illustrates cooperation between immune systems?
it recognizes complement components but via a lymphocyte, drawing together innate and adaptive immunity
Activated B cells (TD)
Where does activation/Ag recognition occur and what happens subsequently?
Ag recognition occurs in the follicle (B cell zone)
afterward, B cell migrates to parafollicular zone and receives stimulus from effector CD4 T cells
In the parafollicular zone, B cells interact with ____ cells: what is the absolute requirement for this to occur
what’s the “bolded” message Shynra included on this slide
the B cell MUST express MHC class II peptides to T cell to receive stimulus
a single B cell can be activated by many different CD4 T helper cells
How do T cells activate B cells? What molecules must be present? what is the purpose?
TCR–Ag–BCR + CD40L (T cell)–CD40 (B cell)
(TCR–Ag–BCR)+(CD40L—CD40) =
activation, followed by proliferation, initial antibody product
