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Flashcards in B cell immunity Deck (19):


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.


hyper IgM syndrom

No germinal centers. caused by lack of CD40 ligand. no critical signal for B cells from T cells. No class switching.


germinal centers

class switching and affinity maturation take place here


follicular dendritic cells

hold antigen for B cells to examine. does not process them.


what activates the B cell and allows it to differentiate

antigen binding to B-cell receptor delivers first signal

T helper cell delivers the second signal via CD40 ligand and cytokines