Beyond ABO and human histocompatibility antigen: other histocompatibility antigens with a role in transplantation

In the past few years, there has been an increasing interest in nonhuman histocompatibility antigens as targets of injury in organ-transplant recipients. This increased interest has been spurred by the fact that human-histocompatibility-antigen-identical kidney transplants also undergo immunological rejections.

Polymorphisms within nonhuman histocompatibility antigen genes associated with evoking an immune response to alloantigens are currently being studied for their association with transplant outcome. Studies identify the polymorphic major histocompatibility complex class I-related chain A as one of the important nonhuman histocompatibility antigen antibody targets in kidney allograft rejections. Use of endothelial cells as targets may clarify the specificities of other clinically relevant nonhuman histocompatibility antigen antibodies in graft rejections.

This review summarizes current knowledge of the specificities and associations of nonhuman histocompatibility antigens with graft outcome after transplantation. The aims of current research into the role of nonhuman histocompatibility antigens and their genetics in predicting outcome are to develop an improved insight into the basic science of transplantation and to develop a risk or prognostic index for use in the clinical setting. Undoubtedly, this will continue to be an area of interest in terms of fully understanding the role of nonhuman histocompatibility antigens as targets of immune-mediated injury and the potential for clinical intervention.