HLA matching for kidney transplantation

Abstract

Histocompatibility testing is an essential component of asuccessful kidney transplant program for two fundamen-tal reasons. First, human leukocyte antigens (HLA) playa central role in the cellular and humoral immune re-sponses that determine the outcome of a transplant.Second, the extensive polymorphism of HLA poses amajor barrier to successful transplantation. The role ofHLA matching in renal transplantation is evolving asadvances in immunology increase our understanding ofthe structure and function of HLA and as improvementsin technology have enhanced our ability to distinguishHLA antigens and the antibodies reactive to them.Transplant success rates have increased markedly becauseof the development of better immunosuppression treat-ments for controlling the immune responses that lead totransplantfailure.WenowknowthatthebenefitofHLAmatching varies depending on donor and recipient riskfactors. There are definite differences in the distributionof HLA alleles among various ethnic populations; there-fore, allocation schemes weighted heavily for HLA com-patibility will favor distribution to Caucasian recipientsbecause the majority of deceased organ donors are Cau-casian. Many argue that current immunosuppression reg-imens obviate the benefits of HLA matching altogether,raising the question of whether HLA matching should beused in allocation. In this article, we review potentialeffects of HLA on transplant immunity (summarized inTable 1), HLA matching protocols for kidney transplan-tation (Table 2), confounding factors for HLA matching(Table 3), and allocation issues (Table 4). Recommenda-tions for HLA matching are provided after the conclu-sion.