Module 14 Flashcards
autologous graft
a graft transplanted from one individual to the same individual
syngenic graft
a graft transplanted between two genetically identical individuals
allogenic graft
a graft between two genetically different indivduals of the same species
xenogenic graft
a graft between two indivduals of different species
alloantigens
the molecules recognized as foreign by the cells of the immune system that are found on a graft
alloreactive lymphocytes
the components of the immune system that respond to alloantigens
first set rejection
occurs 7-14 days after the first transplant by rhe conor to recipent
second set rejection
rejection that occurs more rapidly after the secound transplant from the same donor and recipient idnicating a memory response for the grafted tissue this response can be produced by transferring lymphocytes from sensitized host to naive host
what type of immunity causes rejection of the graft
adaptive immunity
what mediates the recognition of alloantigens
polymorphic histocompatibility genes
what is responsible for almost all rejections
MHC molecules
what mhc class is presnted on
mhc class 2
naive t cells in lymph nodes are activated by alloantigens proliferate and become effector t cells
sensitization phase
what type of t cell migrates to translpanted organ and begins the rejection process
effector t cells
co stimulation of t cells that recognize alloantigens is mediated by what
B7 on apcs
hyperacute rejection is mediated by
alloantibodies
chronic rejection is similar to what
DTH
characterized by blockage of the blood vessels entering the graft that begins within minutes or hours of transplant
hyperacute reaction
pre existing alloantibogies bind to endothelial cells and activate what
complement
having the same what minimizes the production of IgM
ABO blood type
hyperacute rejection results from what
preformed IgG alloantibodies aganist donor mhc molecules
accelerated allograft rejection
if alloantibosied are in low numbers rejection occurs slowly over several days
depletion of antibodies adn lymphocytes can
help abo incompatible individuals
acute rejection results in
injury to the graft and associated blood vessels due to alloreactive t cells and alloantibodies
acute rejection can tak
several days to years
mechanisms of acute rejection
ctl mediated killing of graft cells and direct injury by binding of alloantibosies
principle mechanism of ctl mediated killing of graft cells
acute cellular rejection
what is the characteristics of acute cellular rejection
infitrates of cd8 ctls specific to graft alloantigens
activated cd4 t cells adn ctls do what
produce cytokines that recruit inflammatory cells to graft
what happens if alloantibodies bind to hla molecules on vascular endothelial cells
injury and thrombosis that injures the graft
what is the result of alloantibodies binding to hla molecules
complement activationand the recruitment of neutrophils and platelets
transmural necrosis of the graft vessel walls
histological hallmark of alloantibody medaited accute rejection
marker of hyperacute rejection
occlusions
marker of rejection in antibody mediated rejection
identification of c4d fragmetns in capillaries of renal allograft
most failure of graft transplantation results from
chronic rejection
arterial occulsions is a dominat feature of
chronic rejection
what causes arterial occlusions
proliferation of smooth muscle cells that results in ischemic damage
accelerated gradt arteriosclerosis/ graft vasculopathy
arterial changes
arterial changes are seen in
failed cardiac or renal graftes and can develop after 6-12
what are the main agents to prevent or treat graft rejection
immunosupressive drugs that kill orinhibit t cell activation
inhibitors of t cell signalling pathways
cyclosporine and FK506
what blocks activation of NFAT and IL-2
cyclosporine and fk506
mTORC1
rampamycin inhibits
mycophenolate mofetil
kills proliferating t cells
CTLA-4 to IgG Fc receptors bind B7 and
block interactions with t cells
the activation of t cells during indirect alloantigen responses requires that apcs be activated and express co stimulatory molecules t or f
t
