Transplant Immunology Flashcards
What is an autograft?
Tissue transfer in the same individual
What is a syngeneic (iso) graft?
Transfer of cells or tissues to a genetically identical individuals (like twins)
What is an allograft?
Graft between genetically nonidentical individuals of the same species
What is a xenograft?
Transplant of different species
Recognition of transplanted cells as either self or foreign is determined by… and what are they?
Transplantation antigens
- MHC Ags
- Minor histocompatibility Ags
- ABO blood groups
Direct vs indirect allorecognition
Direct: cytotoxic T cells from recipient bind to foreign HLA antigens of allograft and release cytotoxic factors
Indirect: host APCs present foreign MHC antigens
Rejection mechanisms: hyperacute
Minutes to hours
- recipient’s preformed antibody
- ABs against ABO, HLA, endothelial Ags
- Rare
Rejection mechanisms: acute
- Weeks after
- T cell mediated, some antibodies
- MHC mismatch: faster acute rejection
- mHA mismatch: slower
Rejection mechanism: chronic
- Delayed type, 1 or more years
Hematopoietic stem cell transplant precautions
You have to wipe out prior immune system then replace with donor bone marrow, which makes a new (foreign) immune system
Rejection mechanisms: GVHD graft vs. host disease
Mature donor T/NK cells may be in the bone marrow
- new immune system can attack the original host body
- Skin, GI, liver
- Can be acute or chronic
When is GVHD good?
It can be used for leukemia treatment and helps eliminate residual recipient cancer cells
- Mediated by T/NK
How to determine if a transplant is going to be successful?
- Mixed lymphocyte reaction
- HLA antibody screening and ID (they can cause hyperacute graft rejection)
Immunosuppressive agents
- Corticosteroids: anti inflammatory
- Antimetabolites: anti lymph maturation
- Calcineurin inhibitors: cytokine synth in T cells
- Monoclonal Abs: T/B function by binding to surface
- Polyclonal Abs: deplete thymocytes/lymphs
