adaptive immune response Flashcards
what does adaptive immunity require
lymphocytes/antibodies
why is active immunity needed
some microbes can evade innate
intracellular viruses/bacteria hide from innate
need memory to specific antigen
T cells evolution
mature in thymus
circulate to secondary lympoind
B cells evolution
mature in the bone marrow
circualte to secondary lympoid
name antigen presenting cells
dendritic
macrophages
B cells
APC evolution
mature in bone marrow
circulated to tissue
(then secondary if activated)
what are secondary lympoids
sleep
lymph nodes
MALT
what does cell mediated immunity requrie
antigen presenting cells
T cells
MHC(major histocompatibilty complex)
intrinsic/extrinsic antigen
what do T lymphocytes respond to (T cell receptor)
intracellular presented antigens (not soluble antigens)
antigens with complex with MHC
what happens to self recognising T cells
destroyed in foetal thymus
T cell receptor structure
heterodimers
what happens for T cell receptor to match with foriegn antigen
infected cell has viral protein
viral protein is broken down into peptide
peptide is displayed by MHC moleucle
T cell with TCR has the shape to match peptide with MHC
what is major histocompatibility complex coded from
human leukocyte antigen genes
what are the different types of MHC and where are they found
MHC 1 - on all nucleuted cells
MHC II - only on antigen presenting cells
MHC III - codes for complement proteins
MHC I and II structures
I - 3 domains with extra domain
2 - tetradimer
how do APC display Ag
bug detected by receptors
internalised into phagosome
small part is displayed with MHC II
T cell Ag recognition and activation
T cell receptor binds to antigen on APC
CD4 or CD8 also binds to the MHC II molecules
what are T cells before activation
naive T cells
what happens after T cells are acivated
receptors dimerase
phosphorylaton inside T cells
leads to excitability
secretes interleukin 2
what causes further stimulation after T cell acitbation
IL 2 binds to IL2R
what does stimulation of T cells lead to
clonal expansion
differentiation
effector functions memory
what can a naive T cell form
cytotoxic T cell
T helper 1
T helper 2
how is Th1 produced and what does it do
high levels of IL12
helps macrophages
how is Th2 produced and purpose
low levels of IL 12
antibody production
series of how T cells are activated
endothelial cell becomes infected
virus displayed by MHC I on cell
naive T cell with correct TCR will regonise and bind
niave T cell activated as cytotoxic T cell
clonal expansion and movement around body
how do T cells kill cells
secrete performs and granulysin
explain Th1 activation
bacterium taken into phagosome material displayed with MHC II high IL 12 T cell to Th1 cell clonal expansion Th1 secretes toxic molecules to indirectly kill cell
what does Th1 secrete
interfering gamma (protects cells around the virus and activates macrophages)
what do B cells express
membrane bound Ig
where are B cells that recognise self killed
bone marrow
how does a B cell work present the antibody????
antibody bound to B cell via FC receptor
binds antigen which recognises Ab by shape
phagocytosis
presented to T cell??
how do T cells help B cells
APC cell presents to naive T cells
low IL 12 grt primed Th2
bind with B cell with same antigen
Th2 secretes cytokines - B clonal expands
B cell differentiates to plasma cells and memory B cells
how have B cells captured antibodies
mIgR on surface
B cell activation summary
binding of Ag activates cell
go to lymph nodes (proliferate and differentiate)
plasma cells secrete Ab of same specificity but are IgM
later turn to IgG
what do antibodies do
neutralise toxins once bound to AS of enzymes
bind and increase opsonisation
activate complement
how are vaccines created
purified bacteria placed with formalin
what does formalin do to bacterium
loss of toxicity but not epitaphs (shape)
