L12: transplantation immunology and tumor immunology Flashcards
transplantation success is dependent on ___
HLA alloantigens
what is an alloantigen ?
an antigen that is different from person to person
what is an :
autograft :
synergic(isograft):
allograft ( homograft ):
xenograft ( heterograft):
autograft :self graft
synergic(isograft): graft
from person with idential genetic make up ( identical twins )
allograft ( homograft ): graft from same species
xenograft ( heterograft): graft from different species
antigens recognized in antibody formation against alloantigens are both MHC 1 and 2
Describe hyperacute graft rejection .
rejection occurs within minutes ( up to 24 hours).
mediated by pre-existing antibodies
antibodies react against ABO blood group or MHC 1
compliment is activated –> vascular thrombosis
graft remains pale , no vascularization
describe acute graft rejection .
happens within a week to a few months after transplant
injury to graft mediated by alloreactive T cells or antibodies
type IV hypersensitivity
describe chronic graft rejection .
occurs months or years after transplant
involves both cell mediated and humoral immunity
involves arterial occlusion
cytokine IFN Ycauses influx of activated monocytes into graft
when does graft vs host reaction occur?
when transplanting hematopoietic stem cells (7-30 days after transplant )
reaction of graft vs host is directed against ____
minor histocompatibility complex
Which type of HS is graft VS host reactions ?
Type IV
anti-tumor activity is _____ mediated
cell mediated
tumor antigens are presented by ____ and recognized by ______
MHC 1 , CD8 cytotoxic T cells
how can antibodies defend the body against tumors ?
through activation of compliment or through bridging target cells ( FAB) with effector cells ( FC
What are oncogens ?
mutated genes
