Analysis of transplant outcomes after five or six human leukocyte antigen-mismatched living donor kidney transplantation

Background: Recently, the impact of human leukocyte antigen (HLA) mismatch (MM) on graft outcome has diminished since the introduction of potent immunosuppressive agents, whereas previous reports support the notion that greater numbers of HLA matches are beneficial. This study was undertaken to evaluate outcomes after five or six HLA-mismatched living donor kidney transplantations (LDKT). Methods: The authors retrospectively reviewed graft function after 2687 LDKTs performed between June 1984 and February 2010. A database of 1364 living related and 1063 living-unrelated donor (LURD) kidney transplantations was used for this study. LURD kidney transplantations were classified into three groups; (1) zero to one HLA MM (n = 158); (2) two to four HLA MM (n = 851); and (3) five to six MM (n = 54). An acute rejection episode was diagnosed based on clinical deterioration of graft function or biopsy findings. Graft survival was calculated using the Kaplan-Meier method. Results: Graft survivals in the zero to one HLA MM, two to four HLA MM, five to six HLA MM, and one-haplo MM LDKT were not significantly different. The rates of acute rejection episodes within 1 year after transplantation were similar irrespective of the HLA MM; (1) zero to one HLA MM (37.3%), (2) two to four HLA MM (35.3%), (3) five to six HLA MM (33.3%; P =.832). Conclusions: Survival of five or six HLA-mismatched LDKTs was comparable to that of one-haplo MM and relatively well-matched LDKT. The study showed that the presence of five or six HLA MM was not a risk factor for graft survival after LDKT.