Transplantation Flashcards
What is a graft?
A piece of tissue that is transplanted
Grafts can be used in various medical procedures, including organ transplants.
What is a transplant?
A procedure in which an organ/s, tissue or group of cells are removed from one person (the donor) and transplanted into another person (the recipient), or moved from one site to another in the same person.
What is an autograft?
Tissue grafted back onto the original donor.
What is an isograft?
A graft between syngeneic individuals (i.e., of identical genetic constitution) such as identical twins.
What is an allograft?
A graft between allogeneic individuals (i.e., members of the same species but different genetic constitution), for example, human to human.
What is a xenograft?
A graft between xenogeneic individuals (i.e., of different species), for example, pig to human.
What are the risks associated with allografts?
Risk of graft versus host disease (GVHD) and rejection.
What is the most common allograft?
Blood transfusion.
What can result from blood transfusion mismatching?
Haemolysis, intravascular coagulation, chills, and nausea.
What are major antigens that can trigger graft rejection?
Major Histocompatibility Antigens (MHC), also known as HLA in humans.
What are minor histocompatibility antigens?
Antigens such as HY and HA1 that can also trigger graft rejection.
What are the classes of HLA alleles?
Class I (HLA-A, HLA-B, HLA-C) and Class II (HLA-DP, HLA-DQ, HLA-DR).
What is the inheritance pattern of HLA?
Each child inherits one HLA haplotype from each parent, leading to various possible combinations.
What is the probability of a random pair having identical HLA specificities?
Very low.
What percentage of T-cells in normal individuals react with alloantigens?
Upwards of 10%.
What are the two pathways of donor antigen presentation?
Direct and indirect pathways.
What characterizes hyperacute rejection?
Rejection occurs within minutes.
What characterizes acute rejection?
Rejection occurs within several days.
What characterizes chronic rejection?
Rejection occurs within months to years.
What is the pathogenesis of hyperacute rejection?
Circulating antibodies specific for antigens on the graft endothelial cells activate complement and clotting cascades.
What is the pathogenesis of acute rejection?
Graft infiltration with cytotoxic T cells and cytokine-mediated recruitment of other cells.
What are the risk factors for acute rejection?
Degree of HLA (mis)matching.
What is the pathogenesis of chronic rejection?
Not fully understood; can involve lymphocytes, phagocytes, antibody, and complement.
What is HLA matching?
A method to maximize immunological acceptance of the graft by matching donor and recipient antigens.
What techniques are used to identify HLA alleles?
- Serology
- Sequencing or typing
- Cross-matching
What is cross-matching?
A technique used to investigate whether the recipient has previously reacted to the HLA molecules that will be presented on the donor organ after transplantation.
What is the risk of over-suppression of the immune system?
Increased susceptibility to infections, drug side effects, and other diseases.
What are common side effects of ciclosporin?
- Tremor
- Hypertension
- Gum hypertrophy
- Hirsutism
What are the sources of haematopoietic stem cells?
- Bone marrow
- Peripheral blood
- Umbilical cord
What is graft versus host disease (GVHD)?
A condition where donor immune cells attack the recipient’s tissues.
What are common treatments for GVHD?
- High dose steroids
- Immunosuppressants
- Faecal microbial transplant
- Ruxolitinib
What is CMV disease?
Cytomegalovirus disease that most commonly affects the lung, GI tract, eye, liver, or CNS.
What is the most serious complication of CMV pneumonia?
50% mortality rate.
What is PTLD?
Post transplant lymphoproliferative disease driven by immunosuppression, often associated with EBV.
