TOPIC 10. TRANSPLANTATION
1. Definition
Transplantation is transfer of cells, tissue or an organ from a donor to a recipient to replace or restore function. It may be life-saving (e.g. heart, liver) or improve quality of life (e.g. kidney, cornea).
2. Classification by donor–recipient relationship
3. Donor types and organ sources
Living donor: may donate a kidney or part of liver in carefully selected circumstances; requires informed voluntary consent and donor safety assessment.
Deceased donor: organs recovered after death according to legal and ethical criteria, including neurological or circulatory determination as permitted by jurisdiction.
- Organs commonly transplanted include kidney, liver, heart, lung, pancreas and intestine; tissues include cornea, skin, bone, tendons and heart valves.
4. Immunological basis and rejection
The recipient's immune system recognises donor antigens, particularly human leukocyte antigens (HLA), as foreign. T cells and antibodies can injure the graft. Compatibility assessment, crossmatching and immunosuppression reduce but do not eliminate rejection.
5. Pre-transplant assessment
- Confirm indication, expected benefit, contraindications and suitability of recipient.
- Assess blood group compatibility, HLA typing where relevant, antibody screen and crossmatch.
- Evaluate infection, malignancy, cardiovascular risk, organ function, psychosocial factors and ability to adhere to follow-up.
- Assess donor health, voluntariness, surgical risk and organ quality; ensure ethical allocation and consent.
6. Immunosuppression
Induction: stronger initial immunosuppression around transplantation in selected recipients.
Maintenance: commonly combinations of a calcineurin inhibitor (tacrolimus/ciclosporin), an antimetabolite (mycophenolate/azathioprine) and corticosteroids, tailored to organ and patient.
Other agents: mTOR inhibitors and biologic agents may be used in selected regimens.
Risks: opportunistic infection, malignancy (including skin cancers and lymphoproliferative disease), nephrotoxicity, metabolic complications and drug interactions.
7. Complications and follow-up
- Rejection, primary graft dysfunction, vascular or biliary/ureteric complications, infection, drug toxicity and recurrence of original disease.
- Long-term monitoring includes graft function, drug levels where relevant, infection surveillance, malignancy screening, vaccination planning and cardiovascular/metabolic risk reduction.
- Patients require lifelong follow-up and should not stop immunosuppressive medication without transplant-team advice.
Exam point: Allograft rejection is an immune response to donor antigens. Hyperacute is antibody-mediated and immediate; acute is cellular and/or antibody-mediated; chronic causes progressive fibrosis and vascular narrowing.