Transplantation Flashcards
What is the difference between life-saving and life-enhancing transplantation?
Life-saving – other life-supportive methods are not fully developed or other life-supportive methods have reached the end of their possible use e.g. liver
Life-enhancing – other life-supportive methods are less good e.g. Kidneys and dialysis – the organ is not vital but it improves the quality of life e.g. cornea
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
Give an example of an autograft.
Coronary artery bypass graft
What tissues can xenografts be used for?
Heart valves
Skin
What are the two types of deceased donor?
Donor after brain death – brain dead but heart-beating
Donor after cardiac death –non-heart beating donors
What must be confirmed with DBD donors?
Irremediable structural brain damage of known cause
Apnoeic coma that is NOT due to depressant drugs, hypothermia, neuromuscular blockers etc.
Must be able to demonstrate a lack of brain stem function (e.g. pupils both fixed to light)
What must be excluded before harvesting organs from a deceased donor?
Viral infection
Malignancy
Drug abuse, overdose or poison
How are the organs maintained once they’ve been removed?
They are rapidly cooled and perfused
NOTE: absolute maximum cold ischaemia time for the kidneys is 60 hours
What is the difference between transplant selection and transplant allocation?
Selection – access to the waiting list
Allocation – access to the organ
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 5 tiers of patients on the organ transplant waiting list based on?
Paediatric or adult
Highly sensitised or not
What are the 7 elements that are used to decide upon organ allocation?
Main 3:
Waiting time
HLA match and age combined
HLA-B homozygosity
Other 4:
HLA-DR homozygosity
Donor-recipient age difference
Location of patient relative to donor
Blood group match
What are the main obstacles to donation?
Contraindication for use of that organ
Family not approached for consent
Family declined consent
Describe some other strategies for increasing transplantationactivity.
Use marginal donors e.g. elderly and sick
Transplantation across compatibility barriers
Exchange programmes – organ swaps for better tissue matching
Future – xenotransplantation + stem cell research
What are the main antigens that must be considered when determining the compatibility of an organ for transplant?
ABO blood group
HLA
On which chromosome is the HLA gene encoded?
Chromosome 6
What are the two classes of HLA and which HLA subtypes are in each class?
HLA Class I – A, B and C = present on all cells
HLC Class II – DP, DQ, DR = present on specialised immune cells
What are the most important HLA subtypes in organ compatibility?
A
B
DR
NOTE: the fewer the number of mismatches, the better the outcome for the recipient
What are the two types of organ rejection?
T cell-mediated rejection
Antibody-mediated rejection (B cells)
How is rejection diagnosed?
Histological examination of graft biopsy
How is rejection classified based on the time of onset?
Hyperacute
Acute
Chronic
How may organ rejection present?
Deteriorating graft function e.g. rise in creatinine with kidney transplant
Pain and tenderness over graft
Fever
How can rejection be prevented?
Maximise HLA compatibility
Life-long immunosuppressive therapy
List some treatments for Antibody-mediated rejection.
Anti-CD20 antibodies
Bortezomib (proteasome inhibitor)
Anti-complement antibodies
Plasma exchange
IVIg
Splenectomy
