Transplantation Immunology

Explore how immunologic memory to non-self antigens drives transplant rejection, and how Medawar’s experiments revealed compatibility challenges and the path to immune tolerance.

Trace transplantation history from ancient autographs, nose reconstructions, to 1954 identical-twin and 1961 cross-related kidney transplants, underscoring organ availability as the modern barrier.

Identify the 11 tissues and organs that can be donated from living or deceased donors, and learn how donor type, compatibility, and organ type affect graft survival.

Learn about autografts, isografts (monozygotic twins), allografts, and xenografts in transplantation immunology, and how donor eligibility and recipient priming influence graft acceptance.

Corneal transplants offer high success due to immune privilege and avascular tissue with low MHC expression. Surgeons place small, central grafts, typically without immunosuppressants, and remove sutures after three months.

Learn about bone transplants and grafts, donor criteria—infection-free bone, no IV drug use, and no prolonged steroid or growth hormone therapy—to repair fractures, spare limbs, and restore motor function.

Intestinal transplant replaces the small intestine to treat intestinal failure, either as an isolated transplant or composite allograft. The first successful procedure occurred in Canada in 1986, highlighting its rarity.

Explore liver transplantation as treatment for end-stage liver disease and acute liver failure, covering donor-recipient matching, immunosuppression, biliary complications, and advances in storage and xenotransplant research.

Match lungs by HLA and blood type, ensure identical bronchial circumferences, and preserve the organ with a device during immediate transport; immunosuppression prevents rejection, and lungs pair with heart transplants.

Explore how kidney transplantation relies on donor–recipient matching, including MHC class II antigen compatibility, for allogeneic grafts, while managing immunosuppressive therapy and infection risk.

Investigate heart and heart valve transplantation, from the first allograft in 1967 by Dr. Christian Barnard to donor criteria, immunosuppression, and research in gene therapy and synthetic valves.

The pancreas transplant, either whole or as islet cells of Langerhans, offers insulin independence for select type 1 diabetics and some type 2 cases, often with simultaneous kidney transplant.

Skin's high immunogenicity stems from abundant antigen presenting cells and MHC class one, drives pretransplant immunosuppression and the use of non immunogenic substitutes like bio brain, Integra, and Dermagraft.

Replace bone marrow with hematopoietic stem cells from autologous or allogeneic sources, including cord blood, to reconstitute blood cells and immune function in multiple myeloma and lymphoma, considering donor matching.

Explore sources of stem cells for transplant, including autologous tissue engineered cells, traditional iliac crest marrow aspiration, peripheral blood stem cell collection via apheresis with G-CSF, and umbilical cord blood.

Engraftment marks successful bone marrow transplant as the recipient begins producing new blood cells within two to four weeks after homing, lodging, and engraftment.

Complications in organ and stem cell transplantation include rejection and infection, with infectious agents like cytomegalovirus and Epstein-Barr virus, and risks of cancer, osteoporosis, diabetes, hypertension, and hypercholesterolemia.

Assess donor-recipient compatibility to improve graft survival and reduce complications. Use histocompatibility testing systems to identify antigen matches and delay rejection in allogeneic transplants.

Analyze major histocompatibility complex antigens and their role in transplantation compatibility, focusing on HLA class I and II antigen presentation. Provide insight into donor–recipient matching amid extensive allelic polymorphism.

minor histocompatibility antigens are not hla proteins but show amino acid variation and can be recognized by foreign cells, including y chromosome antigens, and are weaker than immuno dominant masses.

Examine ABO blood group antigens, preformed IgM antibodies, and complement activation in transplantation, stressing blood type and MHC compatibility for graft survival.

Understand allorecognition as host T cells recognize graft antigens through direct and indirect pathways, aided by donor passenger leukocytes and antigen presenting cells, leading to potential graft rejection.

Direct recognition activates cd8 cytotoxic T cells that bind graft or passenger donor APCs, such as dendritic cells or macrophages, displaying MHC, triggering perforin release and apoptosis in graft cells.

Orchestrate indirect allorecognition by signaling other cells to kill through cytokines released by helper T cells. Present graft antigens to T cells, triggering cytotoxic and delayed type hypersensitivity responses.

The immune system recognizes the graft and triggers rejection. Rejection appears as hyperacute, acute, or chronic, with first set and second set phases defining the transplantation-specific process.

Explore the first-set allograft rejection in non-sensitized hosts, where T cells activate and infiltrate the graft, causing thrombosis and necrosis within 10–20 days.

second-set rejection speeds the cellular response, destroying the graft within five to six days and revealing immunologic memory to transplant antigens.

Explore hyperacute rejection in transplantation, driven by preformed antibodies to donor antigens, and watch how blood type incompatibility and cross matching prevent rapid ischemia and tissue necrosis.

Accelerated rejection occurs within days due to donor-specific antibodies and prior sensitization. It activates T cell-mediated memory, antibody and complement responses, causing inflammation, vascular blockage, fever, and donor organ loss.

Explain acute rejection after transplantation as a weeks-to-months process driven by direct T cell recognition of graft antigens, CD8-dominated, with antibody-mediated components causing complement activation and necrosis.

Chronic rejection is a slow, immune-mediated graft loss driven by type three and type four hypersensitivity, indirect recognition, and immune complexes causing progressive fibrosis and vascular narrowing after transplantation.

Explain graft versus host disease (GVHD) as donor graft cells attacking the host in immunocompromised patients, with risk factors like bone marrow or blood product grafts and HLA differences.

Spot graft-versus-host disease within 100 days post transplant by rash, weight loss, and jaundice, distinguishing acute from chronic forms; looka reduction removes T cells to prevent it.

Learn how preventing GvHD relies on irradiated blood and bone marrow products to deplete mature immunocompetent lymphocytes, with recipients categorized into high, intermediate, and low risk.

Explore immunosuppressive agents that enable transplant tolerance by targeting t cell and b cell activation and cytokine signaling, enabling graft acceptance while preserving overall immune function.

Administer corticosteroids to treat acute graft rejection by blocking cytokine production and inducing tolerance; cyclosporine inhibits cytotoxic t cell activation, while azathioprine remains a classic antirejection therapy with adverse effects.

Tacrolimus and sirolimus are fungus-derived immunosuppressants; tacrolimus inhibits calcineurin to block T cell activation, while monoclonal and polyclonal antibodies target CD25 and CD3, with serum sickness risk.

Learn how histocompatibility testing and lab work including donor typing, blood typing, and cross-matching guide donor-recipient matching and graft acceptance in transplantation immunology.

This lecture explains HLA typing as phenotypic or genotypic identification of HLA genes to find donor-recipient compatibility, considering blood type and infections, and selecting donors with the least HLA mismatches.

Identify the most compatible donor using HLA phenotyping by comparing A and B antigens; the friend number two is the closest match, lacking antigens the patient has antibodies against.

Explore HLA genotyping in organ transplantation through PCR-based DNA typing, primer-driven amplification, gel electrophoresis, and DNA-probe hybridization to accurately identify donor and recipient HLA matches.

Learn how an enzyme-linked immunosorbent assay detects patient antibodies against HLA antigens by binding purified antigens to microtiter plates, adding enzyme-labeled antibodies, and measuring color change.

Explore flow cytometry to detect antibodies and analyze antigen-coated beads using fluorescent dyes, laser detection, and light scattering, with data interpreted to identify specific HLA 11 antibodies.

Trace the evolution of transplantation from autographs and allografts to animal organ use, and explain gene modification and transcription factor programming to curb rejection and address donor supply.

Explore immune tolerance in transplantation, including direct and indirect recognition, central and peripheral tolerance, and strategies to achieve long-term graft acceptance through donor–recipient compatibility and HLA typing.

Explore the basic principles of transplant immunology and learn to apply these concepts in your field of work in the future.