Transplant Immunology: Basic Immunology and Clinical Practice

Abstract

Engraftment of a transplanted organ into an allogeneic host triggers a cascade of immunologic responses in the host that are designed to facilitate graft rejection. Modern donor-to-host matching techniques and immunosuppression protocols have successfully tempered this natural immune response so that graft survival has dramatically improved. However, optimizing graft survival by precisely downregulating the host response to graft rejection while preserving host immune defenses against pathologic and infectious agents remains poorly understood and elusive in current clinical practice. This review discusses transplant immunology with respect to host versus graft and the basis of allorecognition, as well as clinical management of the transplanted allograft. Figures show human leukocyte antigen (HLA), direct allorecognition, T cell receptor and CD3, T cell–associated second messenger signaling pathway, CD8 molecules directly ligating class I HLAs and CD4 molecules directly binding HLA class II, detection of alloantibodies by enzyme-linked immunosorbent assay or flow cytometry, recipient-donor crossmatch, histopathology of kidney allograft with antibody-mediated rejection, and an algorithm for assessment and management of renal allograft rejection.  This review contains 9 figures, 6 tables and 61 references. Keywords: Transplantation, immunology, human leukocyte antigen, crossmatch, donor, acute rejection, chronic rejection