Transplantation: part 3 Flashcards
What is the difference between transplant selection and transplant allocation?
Selection – access to the waiting list Allocation – access to the organ
Describe how to solve problem of an organ being transplated from a donor of incompatible ABO blood type
- Remove the antibodies in the recipient (plasma exchange)
- Good outcomes (even if the antibody comes back)
- Kidney, heart, liver
What are the disadvantages of immunosupression
Infection
Tumours
Drug toxicity
What are the two types of organ rejection?
T cell-mediated rejection Antibody-mediated rejection (B cells)
What do cytotoxic T cells and macrophages do
•“Cytotoxic” T cells:
–Release of toxins to kill target(e.g.•Granzyme B)
–Punch holes in target cells(via Perforin)
Apoptotic cell death(via •Fas -Ligand)
Macrophages:
Phagocytosis
Release of proteolytic enzymes
Production of cytokines
Production of oxygen radicals and nitrogen radicals
What usually hppens in antibody mediated rejection of the graft
Usually a type 2 hypersensitivity reaction where antibody binds to antigen on the gra, and aactivats complement, leading to lysis and graft destruction
What is the nationwide system of transplant allocation based on?
Equity – fairness Efficiency – what is the best use of the organ in terms of patient and graft survival?
What are the 7 elements that are used to decide upon organ allocation?
Waiting time, HLA match and age combined, HLA-B homozygosity, HLA-DR homozygosity ,Donor-recipient age difference ,Location of patient relative to donor, Blood group match
Bold items are the most important
How is rejection classified based on the time of onset?
Hyperacute, Acute ,Chronic
Why is living donation encouaged from related family members
It decrease chances of HLA tissue mismatch.NOTE: the fewer the number of mismatches, the better the outcome for the recipient.
Describe Post transplantation malignancy as a result of immunosupression
- Skin cancer
- Post transplant lymphoproliferative disorder – Epstein Barr virus driven
- others
Give an example of an autograft.
Coronary artery bypass graft
Describe structure if MHC class 1 and class 2 molecules
What tissues can xenografts be used for?
Heart valves ,Skin
What are the different types of transplants?
Autograft – within the same individual Isografts – between genetically identical individuals of the same species Allograft – between different individuals of the same species Xenograft – between individuals of different species Prothetic graft – artificial material e.g. plastic, metal
