Lecture 26: Transplantation and Transfusions Flashcards
______polymorphism is the reason why organisms can respond to many antigens but also the reason why it can be hard to find a suitable donor
MHC
MHC class ____ is found on all nucleated cells & presents endogeonous antigens to CD8 Tcells
MHC Class I
MHC class ____ are found on APCs and present exogenous antigens to CD4 T cells
MHC Class II
MHC class _____ are associated w/ complement proteins and other genes
class III
transplantation of tissue b/w sites WITHIN one individual
Autograft
skin graft to cover a wound
no rejection
transplantation of itssue from a genetically identical individual
Isograft
organ transplant from identical twin
transplant of tissue from a member of the same species
Allograft
typically organ transplant b/w genetically distinct individuals
rejection within 1-2 weeks
Xenograft
transplant of tissue from member of diff species
rejection within hours
ethical concerns
pathogen transfer
without _____, all grafts except autographs will eventually be destroyed
immunosuppression
characteristics of transplant rejection
- immune responses against donor MHC
- involved cellular and humoral components
- loss of transplanted organ
donated tissues contain” _____” leukocytes
passenger
may migrate out of tissue
hyperactue rejection occurs within______hours
48
accelerated rejection occurs in up to _____days
7
acute rejection occurs after _____ days
7
chronic rejection occurs after…
several months up to years
in acute rejection, MHC incompatability triggers
T recc response
in acute rejection, RBC antigen incompatability triggers
Antibody response
Pathophysiology of acute rejections
- MHC and RBC antigen incompatability
- cytotoxic T cell infiltration
- Damage to endothelial cells
- thrombosis of vessels
- loss of blood supply to organ
- can be exacerbated by surgical trauma
in acute rejection, DC cells present antigen to Th1 cells which then secrete ______ and activate_______
secrete IL-2 & INF-y
activate cytotoxic T cells and NK cells
Cytotoxic T cells respond to
foreign proteins
NK cells produce ____and _____
INFy and TNF-a
TNF-a activates effector cells (macs,NKs)
blood group antigens stimulate ______cells causing antibody production…“natural” antibodies can cause hyperacute rxn
Th2
what are the 2 pathways of rejection
Direct pathway (occurs early/accute)
Indirect pathway (occurs later/chronic)
Direct pathway rejection
- recipient T cells enter graft and respond to foregin MHC on donor cells
- T cells attack graft vascular endothelium
- vessel destruction + thrombosis
