6-ANTIGEN-MATCHED TRANSPLANTS - CAUSES OF FAILURE

The causes of failure were studied for 1386 cadaver kidney transplants shared through the UNOS 6-antigen match program from November 1987 to February 1992. The one-year graft survival for 1004 HLA-matched first cadaver transplants was 88% compared with 90% for parent donor and 78 % for 22,188 HLA-mismatched first cadaveric donors reported to the UNO S Scientific Renal Transplant Registry. The cause of graft loss was im munological in 55% of HLA-mismatched cadaver kidney failures, whereas only 39% of the HLA-matched graft failures were immunological. The fra ction of immunological failures in HLA-matched first transplant recipi ents younger than age 17 was 57% and decreased with increasing age to 14% for recipients older than age 60. Death with a functioning graft a ccounted for 50% of failures in the older age group. Sensitization was associated with an increased incidence of immunological failures in m atched first graft recipients from 36% in nonsensitized to 53% in broa dly sensitized patients, and 55% of failures were immunological in sec ond graft recipients compared with 39% in first transplants. Some immu nological failures may have been due to tissue typing, since only 18% of failures in kidneys with well-defined HLA antigens were immunologic al, whereas 44% of kidneys matched with more difficult HLA antigens we re lost due to immunological causes. The results indicate that phenoty pically identical cadaver renal transplants have a reduced rate of imm unological failures. As the accuracy of this tissue typing for the mor e difficult HLA antigens improves, immunological failures in this grou p of transplants will decline even further.