B cell immunity Flashcards
IgD
role is to ensure autoreactive cells don’t get out into the periphery
rearranged heavy chain and surrogate light chain
signals end of heavy chain rearrangement, cell survival, cell proliferation
leads to light chain rearrangement
RAG-1 and RAG-2
involved during heavy and light chain rearrangement
Immature B cells in bone marrow
no reaction with self antigen leads to B cell moving to the blood and expressing IgD and IgM.
reaction with self antigen leads to immature B cell retained in bone marrow (undergoes receptor editing)
receptor editing
rearrangement of light chain genes that occurs when B cell reacts to self antigen in bone marrow
allows immature B cell to make a new light chain, IgM with different specificity
what happens when B cell sees antigen without T cell help?
B cell dies or becomes totally unreactive
what happens if B cell fail to enter lymphoid follicles?
it dies. B cells have half life of 3 days
dendritic cells
takes infection from site of infection to lymph node to stimulate adaptive immunity.
how do B cells see antigen
natively. by binding to the entire antigen, it can produce a more effective antibody
TI-1 antigen
does not activate T cell. can activate B cell. results in innate response, no T cell response.
bacterial lipopolysaccharide, brucella abortus
TI-2 antigen
does not activate T cell. can activate B cell. results in innate response, no T cell response.
pneumococcalpolysaccharide, salmonella
without T cells
no immunologic memory, no memory B cells, no IgG, only IgM responses, responses are short lived
how can B cells be activated without T cells?
For TI-1, TLR4 (toll receptor) is a signal that can replace T-cell signals
For TI-2, by crosslinking of their receptors by antigens. repeated antigen increase signal to B cell.
memory cells
IL-4 from T-cell allows memory cells to differentiate. results in a cell that can grow, proliferate and stimulate T cells.
plasma cells
IL-10 from T-cell allows plasma cells to differentiate, results in a cell that does not grow, proliferate, and cannot stimulate T cell. High rate of IgG secretion.
