HLA complex: brief history, general characterization and impact on kidney transplantation

Abstract

Since the beginning of renal transplantation, the incompatibility of tissues between donor and recipient is known to be one the key barriers to a successful procedure, predisposing significantly to rejection episodes. The importance of human Major Histocompatibility Complex (MHC)/Human Leukocyte Antigen (HLA) complex in kidney transplantation, is reviewed in this article. The chosen articles reveal the most important moments and achievements in this field, since the beginning of the 20th century. This review is divided in four major topics, which englobe the main goals of this article: the history behind the discovery of the HLA; the general characterization of the HLA complex, emphasizing the relevant aspects of HLA-class I and HLA-class II structure, genetics and main functions; the impact of the HLA complex matching in kidney transplantation, including an explanation of its mechanisms and role in hyperacute rejection, cell-mediated acute rejection, antibody-mediated acute rejection and chronic allograft dysfunction; the more recent aspects on how to proceed to the immunological study of a patient before, during and after a renal transplantation, discussing the pros and cons of each step and techniques used, and the newest discoveries in the field. The progress achieved in understanding the link between HLA complex and renal transplantation has been shown to radically improve graft survival and to reduce the incidence of rejection episodes. However, there is still a long way to improve, as the impact of the non- HLA antigens remains misunderstood and as more efficient methods to study the patients still under discussion.