NEW APPROACHES TO DONOR CROSSMATCHING AND SUCCESSFUL TRANSPLANTATION OF HIGHLY SENSITIZED PATIENTS1,2

Abstract

A class I HLA molecule may bear not only a private or unique determinant, but a shared, yet discrete, public epitope. These public determinants occur with a much higher frequency in the random donor population than the associated private determinants, are encountered more often in random donor blood transfusions and in renal transplantation. Sera from highly sensitized dialysis patients contained a restricted number of antibodies to public determinants rather than a diverse array of antibodies directed against the private HLA-AB epitopes. Comprehensive serum analysis of the public antibodies in highly sensitized transplant candidates has optimized identification of potential crossmatch-compatible donors and has avoided needless crossmatches. During the past 2 yr, the incidence of renal transplantation from cadaveric donors to highly sensitized recipients doubled. At 10-25 mo. following transplantation, 70% of these allografts are functioning. Private HLA class I antigen incompatibility was not a barometer for exclusion in the final donor crossmatch of these highly sensitized recipients. Positive donor T cell crossmatches with sera obtained more than 6 mo. prior to transplantation may not represent an impediment to successful transplantation. The approach of detailed antibody analysis can result in an improved outlook for successful transplantation of more dialysis patients who are highly sensitized to the class I HLA alloantigens.