Transplant Immunology Flashcards
What are autografts?
Grafts of the same individual exchanged from one part to another part of the body
What are isografts?
Grafts exchanged between identical twins of identical genetic constitutions
What are allografts?
Grafts exchanged between non-identical members of the same species
What are xenografts?
Grafts exchanged between members of different species
Susceptible to rapid attack caused by naturally occurring Abs that activate complement
Human HLA genes inserted into the genomes of the donor animals increase the changes of successful transplantation
The outcome of transplantation is determined by what?
Condition of the allograft
Donor host antigenic disparity
Strength of host anti donor response
Applied immunosuppression
ABO matching is not important for which types of transplants?
Cornea, heart valve, bone and tendon transplants because these tissues have limited access to immune cells
ABO incompatibility doesnt affect which cell type?
Stem cell transplantation
Which Ags are present in type A blood?
Ag A
Which Abs are present in type A blood?
Anti B
Which Ags are present in type B blood?
Ag B
Which Abs are present in type B blood?
Anti A
Which Ags are present in type AB blood?
Ags A/B
Which Abs are present in type AB blood?
None
Which Ags are present in type O blood?
None
Which Abs are present in type O blood?
Anti A/B
What occurs in direct allorecognition?
Recipient T cells arrive into the graft and recognize intact allogeneic MHC molecules on donor APCs in the graft
What occurs in indirect allorecognition?
Donor MHC molecules are taken up, processed and presented by the recipient APCs for activation of recipient T cells
What are the effector mechanisms of graft rejection?
Th2 type (IL-4 and 5) humoral rejection mediated by Abs Th1 type (IL-2 and IFN-gamma) cell mediated rejection by CD8 T cells
What is the onset for hyperacute host vs graft rejection?
Immediate
What is the mechanism and vessel histology of hyperacute rejection?
Preformed Abs directed against the donor tissue
Caused by accidental ABO blood type incompatibility which is very rare
Presents while still in surgery with thrombosis and occlusion of graft vessels
What type of hypersensitivity occurs in hyperacute rejection?
type II
What is the onset for acute host vs graft rejection?
Weeks to months
What is the mechanism and vessel histology for acute rejection?
T cell mediated immune response directed against the foreign MHC
Inflammation and leukocyte infiltration of graft vessels results
Most common type
What type of hypersensitivity occurs in acute rejection?
Type IV
