Lecture 10: B Cell Immunity Flashcards
What are the 3 kinds of B cells?
1) B-1
2) B-2
3) MZ (marginal zone)
Most adaptive responses are mediated by _____. (the other 2 types are innate-like)
B-2
Where are MZ cells located?
spleen
Where are B-1 cells located?
body cavities (peritoneal, pleural)
What are the only B cells that have memory?
B-2
Why is snake venom so lethal?
because it is usually delivered at such inconsequential doses that it goes undetected by adaptive immune system
____ mediates the primary response while ____ mediates the secondary response
IgM; IgG
True or false: the larger the antigen, the more immunogenic it is
True
so since insulin is so small, doctors were able to get away with giving small doses of porcine insulin
What is the site of greatest immunogenicity of injection?
subcutaneous > intraperitoneal > intravenous > intragastric
What are adjuvants and what is a common one used in human vaccines?
make antigens insoluble to elicit a larger, more potent immune response
Alum
How does Alum work to increase immunogenicity?
delays release of antigen; enhances macrophage uptake
True or False: Most B cell responses require T cell help for activation?
TRUE
How do B cells recruit T cells?
BCRs interact with antigen –> antigen is internalized with BCR and degraded. Peptides associate with MHC-II and go to surface of B cell. TCR on T cell recognizes peptide in context of MHC-II and is stimulated to produce cytokines which activate B cell to proliferate into Ab-producing cells
What 3 signals are required for activation of B cell?
1) interaction of BCR with antigen
2) interaction of TCR with peptide/MHC-II
3) ineraction between costimulatory molecules CD40 (B cell) and CD40L (T cell)
T independent antigens are usually __________
polysaccharides
Once a B cell interacts with a T cell, the T cell secretes B cell stimulatory cytokines like _____, ______, and _____ as well as expresses _______.
IL-4
IL-5
IL-6
CD40L
True or False: B and T cells must recognize the same antigen
TRUE (but not the same epitope)
B cells recognize native epitope
T cells recognize peptide ALWAYS in the context of MHC
How do you immunize babies against carb antigens if those are T-independent responses?
trick immune system to exploit babies’ ability to make a T-dependent response (which responds to proteins)
attach carb from flu to tetanus toxin
How do you immunize babies against carb antigens if those are T-independent responses?
trick immune system to exploit babies’ ability to make a T-dependent response (which responds to proteins)
attach carb from flu to tetanus toxin
Primary response is ______ (IgM)
Secondary response is ______ (IgG)
slow
fast
Why does affinity increase so much after primary response?
somatic hypermutation and higher antibody titer
Are lipids or nucleic acids immunogenic?
NO
Isotype switching occurs by rearrangement of the ____ gene
CH
When does isotype switching occur?
during T-dependent responses (regulated by T-cell cytokines)
