b lymphocytes Flashcards
at what stage do B lymphocytes become tolerized to self and die off
at the immature b cell stage
what type of antibodies does an pre and immature b cell have
Mu chains no delta yet
what happends to a b cell once it is activated by gamma interferon
it will start deviding and beom a plasma or memory cells
what do plasma cells do and some characteristics
secrete antibodies, only live a few days elongated nucleues and pernucluear halo
what are the three things that b cell antibodes will do to an antigen
opsinizatin for phagocytosis, direct nuetrization, and activate the compliment pathway for apoptosis
what is the diffence between thymus dependent and thymus independent antigens
thymus dependent are proteins whereas the independent are non proteins and do not need a Th cell for activation
name one Ti-1 or thymus independent antigen
LPS or lipopolysaccharide binds a non immuniglobulin recepot and promotes polyclonal expansion
what do Ti-2 antigens do
they bind b cell surface immunoglobluin at several epitopes
what is the net result with all Ti thymus independent cell activation
no memory cells isotype switching nor affinity maturation .
what helps to transduce the signal across the membrane in B lymphocytes
Ig alpha and Ig beta
what is another name for the light chains in a b cell
kappa or lambda light chains
what did dryer and bennett postulate could happen to the varaible reagions of b cells
gene rearrangement
what segments of the varaible region do heavy and light chains have
heavy VJD light just VJ
how many combiniations are possible thorugh gene rearragment and other mechanisms
ten billion
what is junctional diversity in the variable region
when nucleotide addition or removal occurs at joints between gene segments
what is somatic mutations in varaible regions
point mutations that will occur that the body allows to happen
what happends to the genes as the cells go from germline to differentiated
germilen has all genes then some are lost through recombinases and excision and cannot come back
what chain rearranges first and whats the order
the heavy chain, randome Dand J then comes the V
what is the order of the light chain rearrangment
kappa kappa lambda lambda it will try both kappas before it will try a lambda to get a working segment
overall arrangment order
heavy chain from one parent then other If needed then one Kappa then second kappa then lambda until it works
how are Img and IgD specific for the same antigen in a b cell
they are both next to each other transcriptionally and will just splice diffently
how does it switch from membrane form to secreted form
the membran anchor is spliced out of the RNA
how is isotype switching or going from IgG to IgA done
all controled by the cytokines so IL4 will code for IgE IL5 will code for IgA
how does affinity maturation ocure
point mutation in the v region will give rise to better binding over time because smaller amounts will induce a response and positve feedback loop
