The changing role of HLA matching.

1. In the precyclosporine era, there was a 12% difference in graft survival at one year between recipients of HLA identical and one-haplotype mismatched transplants from living-related donors. This difference increased to 20% at 5 years. 2. Recipients of cadaver donor transplants which were not mismatched at HLA-A,B antigens had a 10% higher graft survival rate at one year than recipients of kidneys which were completely mismatched at HLA-A,B. The difference increased to 17% at 5 years. 3. Patient survival at 5 years posttransplant was 5% higher in recipients of HLA-A,B matched grafts than in recipients of completely mismatched grafts. 4. The percentage of zero HLA-A,B mismatched grafts which functioned was 7% higher at one day and 10% higher at one month than completely mismatched grafts to sensitized recipients. 5. Sensitization following a rejected transplant occurred two to three times more frequently in recipients who rejected an HLA-A,B mismatched graft and were subsequently retransplanted. 6. Sensitized recipients generally received transplants which were better matched for HLA-A,B antigens as a result of selection against mismatches at the crossmatch. Twenty percent of highly sensitized recipients were transplanted with no mismatches at HLA-A,B. HLA-DR matching was not affected by sensitization. 7. HLA-C locus antigens were typed in 30% of donors and recipients since 1979. Matching for the C locus antigens in addition to HLA-A,B or HLA-DR antigens did not improve graft survival. 8. The number of patients typed for HLA-DR antigens has steadily increased since 1978, with 90% of patients transplanted in 1984 and 1985 typed for DR antigens. 9. Since the introduction of cyclosporine, there has been a significant increase in the number of poorly matched transplants at the expense of well-matched transplants. This trend coincided with a decrease in the number of cadaver donor kidneys shared between distant centers. 10. Matching for HLA-B and -DR locus antigens had a larger effect on cadaver kidney graft survival than matching for HLA-A,B or HLA-DR antigens separately. First cadaver transplants with zero HLA-B,DR antigens mismatched had a 90% one-year graft survival rate when the recipient received cyclosporine. One approach toward increasing the number of such well-matched transplants would involve extensive sharing of kidneys from B locus homozygous donors, since these account for half of the zero HLA-B,DR mismatched transplants.(ABSTRACT TRUNCATED AT 400 WORDS)