HLA-A incompatibility associated with enhanced long-term renal graft survival in HLA-B, DR mismatched transplants.

The effect of HLA-A matching on long-term cadaver kidney graft survival was analysed, on average, 6 years after transplantation in a total of 1085 cyclosporine (CyA)-treated patients. A beneficial effect of HLA-A mismatching on graft survival was found by univariate and multivariate analyses (P < 0.05). Enhanced graft survival was associated with HLA-A mismatching in transplants mismatched for HLA-B,DR (P = 0.03), but not in HLA-B,DR compatible transplants. High 6 year graft survival rates, 78% and 66%, were found in transplants mismatched for two or one HLA-A antigens, respectively, among patients without any acute rejection episode. This was significantly higher than the survival rate of 55% found in HLA-A compatible transplants (P = 0.001). In patients who had suffered from acute rejection episodes, a prolonged graft survival was also associated with HLA-A mismatching in HLA-B,DR mismatched transplants (P = 0.04). The beneficial effect on graft survival of HLA-A mismatching was most pronounced in patients treated with high/medium dose CyA and prednisolone (P = 0.004 overall and P = 0.0007 for HLA-B,DR mismatched transplants). In conclusion, HLA-A mismatching was associated with enhanced long-term renal graft survival in CyA-treated recipients of HLA-B,DR mismatched transplants. In clinical situations, the present results might, if confirmed, contribute to the prolongation of long-term graft survival. The results might indicate the existence of tolerance promoting allogeneic markers within the HLA-A class I region.