Immunobiology of renal transplantation.

The clinical application of our knowledge of the immune barriers to transplantation has advanced allo-organ replacement therapy to the level of routine practice, while simultaneously engendering a critical shortage in available donors. Recent work in xenotransplantation addresses this need. The current understanding of the immune barriers to transplantation has evolved to consider alternate responses to alloantigen, namely acceptance. The delineation and application of recent discoveries in T cell costimulatory events, antigen presentation, and differential T lymphocyte responses are opening pathways towards the development of tolerogenic protocols for use in clinical transplantation. This article presents a review of transplant immunobiology with special attention to antigen presentation and T-cell activation as phases of the immune response relevant to the discussion of transplant tolerance.