ICL 2.2: B-Cell and Ig Flashcards
what is innate immunity?
non-specific, first line defense
cell mediated, some general small molecules
responsible for stimulating adaptive immunity
they’re cells and proteins that you just inherently have in your body
what is adaptive immunity?
very specific, creates long term memory for a pathogen
it will adapt to everything you may come into contact with
humoral & cellular mediated
which cells are antigen presenting cells?
macrophage
dendritic cells
epithelial cells
B cells
what are the regions of an antibody?
if you cut an antibody with a papain enzyme you get 2 Fab regions and 1 Fc region
Fab region = the arms of the Y
Fc region = stem of the Y
what is Fab?
fragment antigen binding
what is Fc?
the fragment that’s constant
it also binds the complement
what’s the difference between the types of Ig?
the amount of glycosylation varies between IgG, IgM, IgD, IgA, IgE
which immunoglobulins are monomers, pentamers and dimers
IgG, D and e are monomers
IgM = pentamer
IgA = dimer
what is x-linked agammaglobulinemia?
they don’t produce any antibodies!!
they have no IgG, IgM, IgD, IgA, IgE
don’t live longer than a year or two…
what is affinity maturation?
you’re mutating the CDR regions of the antigen binding site of an antibody so that it increases the affinity towards the antigen
what 3 signals are required for B cell activation?
- first signal is from from antigen binding/internalization to the B cell receptor
- second signal from TH2 helper cell which deliver CD40/CD40L to the B cell
- third signal from cytokines stimulate proliferation and isotype switching
these three signals are going to induce the B cell to become fully mature and allow for somatic hypermutation to increase affinity to antigen
which enzyme is responsible for somatic hypermutation?
AID
without it, the B cells can’t become fully activated
what are germinal centers?
where long-lasting B cell-T cell interaction happens
induce hyper somatic mutation and isotype switching
this is where you develop a good antigen specific response!
what does a swollen lymph node indicate?
the germinal center is growing because you’re doing induce hyper somatic mutation and isotype switching so that you can have a specific targeted response to whatever antigen is making you sick`
what happens in the germinal center?
in the light zone are follicular dendritic cells which are specialized dendritic cells that capture pathogens but doesn’t pagocytose it using complement
the follicular dendritic cells are waiting for B cells to come bind to them = signal number 1 for B cell
then once T cell comes along to help = signal 2
is somatic hypermutation always good?
no!
sometimes the hypermutation produces B cells with a lower affinity for the pathogen
then the B cell can’t present antigens to T cells and the cell dies via apoptosis
what happens to antigen-bound B cells that are under the influence of an IL-10 secreting helper T cell?
BCR cross-linking with helper T cell which releases IL-10 causes B cells to differentiate into plasma cells
plasma cells then make antibodies until nutrients run out and then they die
what happens to antigen-bound B cells that are under the influence of an IL-4 secreting helper T cell?
BCR cross-linking with helper T cell which releases IL-4 causes B cells to differentiate into memory B cells
they stick around for 60 years
they already have rearranged into a certain isotype and have undergone somatic hypermutation so the next time they’re exposed to a pathogen they recognize, you’ll have an immediate response!
