b cells Flashcards
once a B cell recognizes antigen it synthesizes
antibodies
antibodies attach to pathogens leading to
elimination
variable heavy portion is encoded by
V D & J genes on chromosome 14
two types of B cell activation
- T cell dependent
- T cell independent
T cell dependent requires two signals
- cross linking of receptors bound to antigen
- T cell binding
receptor crosslinking
pathogen binds multiple receptor and clusters them together
B cells present antigen to T cells via
MCH class II
CD40 (B cells) binding to CD40 (T cells) is required for
class switching
B7 (B cells) binding to CD28 (T cells) is required for stimulation of
T cell cytokine production
T cell independent activation is very important for
non protein antigens (polysaccharide & LPS)
T cell independent produces mostly
IgM
conjugated vaccines - polysaccharide antigen
no T cell stimulation
poor B cell memory
weak immune response
conjugated vaccine - peptide antigen
B cells generate antibodies
antibody presented to T cell
T cells boost B cell response
strong immune protection
examples of conjugated vaccines
H. influenza type B
neisseria meningitides
streptococcus pneumoniae
other surface markers on B cells
CD19, CD20, CD21
CD21 is the marker that allows infection by
EBV
