Transplant Immunology Flashcards
What type of hypersensitivity is cell-mediated?
Type II
What process checks to ensure the recipient does not have antidonor HLA antibodies?
Cross-matching
What criteria help reduce the chance of graft rejection?
ABO matching, donors must not have antidonor HLA antibodies, donor should have as close an HLA match to recipient as possible
Acute graft rejection can be prevented using immunosuppressants. Can longterm use also prevent chronic rejection?
No, chronic rejection cannot be prevented with immunosuppressants. The cause of chronic rejection is unknown.
What types of grafts are from the same person?
Auto grafts
A graft is transplanted from one identical twin to another. What type of graft is this?
Iso graft (Syngenic graft)
A recipient rejects an organ from donor 1. Can the recipient receive another organ donation from donor 1?
No. Because T and B cells have memory, any new donation from the same donor will be immediately rejected
What type of graft rejection is a Type IV hypersensitivity?
Chronic rejection
What mediates hyperacute graft rejection?
Pre-existing antibodies (to ABO or HLA)
What are the two pathways for the presentation of graft antigens?
Direct & Indirect
What is the timeframe for chronic graft rejection?
Months to years
What four criteria must be met for transplantation?
- Damage to the body must be irreversible
- Disease must not reoccur
- Chances of rejection must be minimized
- Must be on immunosuppressive treatment
What would happen if mature donor T cells were transplanted along with stem cells?
The donor T cells would begin attacking the recipient cells via activation of host macrophages and NK cells - graft vs. host disease
True/False. Destruction of host cells by graft T cells is always harmful.
False. In some instances, this can be beneficial. For example, in cases of tumor leukemia, the destruction of host tumor cells is a good thing (graft vs. tumor disease)
These MHC are located on all nucleated cells?
MHC I
Why type of hypersensitivity is delayed?
Type IV
What is the principal cause of early graft rejection?
Acute rejection - T cells
Graft vs. host disease is most common with what transplants?
Stem cell and liver transplants - rich in lymphocytes
What are the most polymorphic alleles involved in organ transplantation?
HLA-A, HLA-B, HLA-DR
Acute graft rejection takes place in what timeframe?
Days to weeks following transplant
T cells are the primary mediators in what type of graft rejection?
Acute & Chronic graft rejection
What types of grafts are most successful? Why?
Auto and iso grafts because they they are from “self”
What type of graft is transplanted between species?
Xenogenic graft (Xenograft)
Compatibility between what alleles is important in organ transplantation?
HLA (MHC) alleles
What is the indirect pathway for graft antigen presentation?
Graft MHCs are taken up by recipient APCs and then presented by recipient MHCs
What type of hypersensitivity is graft vs. host disease?
Type IV hypersensitivity
Fibrosis and graft atherosclerosis are primary characteristics of what type of graft rejection?
Chronic graft rejection
What antigens are involved in chronic graft rejection?
Graft alloantigens
What MHC are located only on APCs?
MHC II
A patient receives a kidney transplant from an unknown individual. Within minutes, the recipient begins rejecting the graft. What type of graft rejection is this?
Hyperacute rejection
What is the direct pathway for graft antigen presentation?
Recipient T cells bind directly to donor MHC II located on donor APCs
Grafts are most commonly from genetically different individuals of the same species. What are these grafts termed?
Allogenic grafts
What are the major characteristics of hyperacute graft rejection?
Thrombosis of vessels and ischemic necrosis of the graft
