Lecture 13 Flashcards
(13 cards)
What is the main immune mechanism of tumor eradication?
-kill tumor cells by CTLs specific for tumor antigens
CTL response against tumors are induced by recognition of tumor antigens on which cells?
APCs
How do tumors evade immune responses?
- tumors stop expressing antigens that are targets of immune attack (antigen loss variants)
- stop expression of MHC I molecules
- inhibit T cell activation
- secrete immunosuppressive cytokines like TGF-B
animals identical to one another
syngeneic
one species that differ from other animals of same species
allogeneic
animals of different species
xenogeneic
The antigens of allografts that serve as targets of rejection are proteins encoded where?
MHC
Direct allorecogntiion
- T cells in recipient recognize donor allogenic MHC molecules on graft dendritic cells
- stimulate development of alloreactive T cells that recognize and attack cells of graft
indirect allorecognition
-donor alloantigens are processed and presented by self MHC molecules on recipients APC
hyperacute rejection
- minutes of transplantation
- thrombosis of graft vessels and ischemic necrosis of graft
- complement activation, endothelial damage
- mediated by prefrormed Abs
- barrier for xenotransplantation
acute rejection
- days or weeks
- early graft failure
- parenchymal cell damage, interstitial inflammation, endothelialitis
- mediated by T cells and Abs specific for alloantigens in graft
chronic rejection
- months or years
- progressive loss of graft function
- chronic inflammatory reaction in vessel wall, intimal smooth muscle cell proliferation, vessel occlusion
- fibrosis of graft and arteriosclerosis by T cells which secrete cytokines
Main treatment of rejection of organ transplants?
immunosuppression-inhibit T cell activation and effector functions
