Lymphocyte Function Flashcards
what are lymphocytes
antigen specific
how is specificity achieved
by antigen receptor on cell surface
what is the b cell receptor
cell surface antibody
what are the T cell receptor
t cell receptor (TCR)
what do both T and B cels have
many variants each with different specificity
what are cells of the same specificity
are a clone
what are immunoglobulins sun and secreted by
B cells
what must happen for Ig secreetion
activation by binding antigen
what happens when activated
differentiate into plasma cells
what si the antigen receptor on B cels
antibody that the b cell is programmed to make
what happens when an antigen binds
clonal expansion and differentiation
what are Ab encoded by
multiple genes segments
what encodes VH domains
V-ariable
D-iversity
J-oining
GENES
what encodes the VL domains
V-ariable
J-oining
GENES
what encodes constant domains
C-onstant
GENES
in a heavy chains what is there
V - 50 segs
D - 25 segs
J - 6 segs
what are he first Ab to be encoded
IgM then IgD
what is done to influence Ab diversity
segments aligned and intevreiennig segment spliced and lost - irreversible
what happens after the B cell DNA is spliced
transcription = primary RNA splicing again =mRNA translation = Chain polypeptide
how is additional diversity added by b cell
into mutations into this region
how do Kappa light chains differ from heavy chinas
just V and J segments
all kappa
what is found downstream of kappa light chains
constant kappa region
what do all B cells begin making
IgM
what is class switching
memory cells produce IgG, IgA, IgE with same specificity
what do T cell indept antigens produce
only small amount of IgM Ab
what does Ab responses mostly require to help
T cells
what are some characteristics fro T cell receptor
on t cell surface recog antigen
structurally related to Immunoglobulin
V, D, J, C genes encoding V and C regions
bind to antigenic peptide assc with MHC
what si TCR similar to
Fab fragment of antibody but not identical
what does each T cell have on its surface
about 30, 000 TCR
what are the TCR polypeptide chains
alpha and beta chains
what links TCR polypeptide chains
disulphide bonds
what do majority T cells have
alpha/beta TCR
what does the minority of T cells have
alternative struct similar but is gamma/delta T cells
whats typical TCR structure
3D
V - alpha
V - beta
have hypevaribale loops or CDR’s
what are the hypervraible loops repsonsisbelfor
detecting antigenic peptide in combination with MHC
how does MHC class I and TCR bind
peptide from virally infected cell to top of MHC class I and detected by TCR
on helmet T cells associated wth
CD 3
CD 4
on cytotoxic T cells TCR assc with
CD 3
CD 8
what si the TCR complex composed of
TCR - alpha nd beta chinas
CD 3 - gamma, epsilon and zeta chains
what si CD 4 structure like
4 globular domains
what is CD 8 structure like
bulb
what des pairing of accessory molecules do
stabilises interaction and provides co stimulaiton
what does t helper cels do after binding to antigen
cells secrete growth factors (cytokines) which control immune response
act locally
how do cytokines coordination the response
t helper cells produce interferon
APC release interleukin or other growth factor
what do cytokines do
control and coord immune response
favour macrophage activation and cell mediated responses
stimulate B cells to prod Ab
what is cell mediated cytotoxicity
release perforins form pores in target cell
release other damaging enzymes
release cytokines
