Immunology of transplantation Types of transplantation • Autotransplantation –within one organism • Allotransplantation- between one species • Xenotransplantation- between two different species Success rate of transplantation in humans Downloaded from: StudentConsult (on 4 August 2013 10:57 AM) © 2005 Elsevier Polymorphism of HLA antigens Co-dominant expression of HLA genes Requirements before solid organ transplantation • ABO blood groups compatibility • Negativity of cross match test • HLA „similarity“ (does not play a significant role in heart and liver transplantation) Effect of HLA-identity on kidney graft survival Cross match test • Used for detection of recipient´s antibodies against donor´s antigens (mainly HLA antigens) • Donor´s leukocytes + patient´s plasma • Positivite – antibodies bind to leukocytes – can be detected e.g. by flow cytometry • Positivity contraindicates transplantation Types of graft rejection • Hyperacute - minutes to hours after transplantation. Caused by pre-formed recipient antibodies against HLA antigens of the donor. Irreversible. • Acute -several days to months after transplantation. Mainly T-cell mediated. Usually reversible by aggressive immunosuppression. • Chronic - years after transplantation. Continuous decrease in graft function. Irreversible. Mechanism unknown. The most frequent types of organ transplantation • Heart • Kidney • Liver • Lungs • Pancreas • Cornea • Many other organs • Extremities, face… Hematopoietic stem cells transplantation • Indications: malignancies, bone marrow failure, primary immunodeficiencies. • “Whole“ bone marrow or separated CD34+ cells can be used. • The most significant complication: graftversus host reaction (GVHR). • Optimal HLA-matched donor is required. Graft-versus host reaction (GVHR) • Immunological reaction of transplanted T-cells against recipients (HLA) antigens. • Skin, liver, intestine predominantly affected. • Milder forms can be treated by immunosuppression, severe forms may be fatal. • Can be induced by transfusion of non-irradiated blood to immunodeficient patients (primary immunodeficiencies, leukemia…).