ch 6 Flashcards
how does an ag travel in the to LN or spleen
by subcapsular sinus macrophage or as soluble ag
how do B cells get ag
actively extract it from apc which isnt requirement but makes it more efficient
cSMAC
ag: bCR
pSMAC
integrins/ adhesion
dSMAC
actin
what signal is on ITAMS
YxxL/Ix(6-8)YxxL/I
what does the phosphorylation on ITAMS do
acts as a docking point for adapter molecules
do B cells need T cell help
yes w some antigens - protein antigen
mice needed bone marrow and thymus grafts for SOME antigens
B cells and antigen vs w t cell help
by themselves induce activation and proliferation
w t cells induces memoryand differentiatino
what does recognition of ag on B cell lead to
upregulation of MHC II and B7 that then binds to CD28 to upregulate CD40
what is CD40 on
the b cell
linked recognition
both b and T cell recognize the same protein
may be different epitopes
what is the purpose fo the GC
b cell activation
how do b cells move in the GC
due to cytokine receptors expression changes
what is a characteristic of GCs
they are heterogenous, sometimes one clone will take over ther ties it will be a micture of clones
where does SHM occur
in GC
what is SHM
individual point mutatinos in heavy and light chains that are followed by selection of the one w best affinity for the ag
AID
activation induced cytidine deaminase that prduces opportunity for mutatinos by altering deoxycytidine bases
occurs after SHM
what happesn in the light zone of GC
B cells activated
apoptosis for b cells wo T fh help and interaction w FDC or ones that react w self antigen
what happnes in the dark zone of GC
SHM and proliferation
IgG and IgM and affinity maturation
affinity of igG higher
undergoes affinity maturation while IgM doesnt bc its a pentamer
affinity of waht antibody changes after infection
igG
differences in antibodies
there are 5 different CH gene sementa nd 5 different heavy chains
what antibodies have a J chain
igA and igM
what antibodies have a hinge region
igG
igD
igA
what regulates class switch recombination
T cells and causes change in isotype
BUT THE ANTIGEN BINDING SPECIFICITY DOESNT CHANGE
differences within isotypes of antibodies
some isotypes have subclasses and all igH can pair with lambda or kappa light chain
