6.1
TITLE: THE EFFECT OF HLA ANTIBODY ON RENAL ALLOCATION IN MINORITIES

Deborah O. Crowe.<sup>1

1</sup>Transplant Immunology, DCI Laboratory, Nashville, TN, USA

The presence of HLA antibody has a significant effect on the rate of renal transplantation and may account for much of the disparity in waiting times found in African Americans. Review of UNOS data shows that an antibody level of 20–79% will increase waiting time 70% and a PRA over 80% increases waiting time 127%. This effect is even more profound if the patients are stratified into primary and re–transplants. For primary transplant recipients, the time to transplant will be increased 50% in patients with PRA 20–79% and will be 75% longer if PRA is 80% or greater. For re–transplants, the time to transplant increases 140% with a PRA 20–79% and will be 300% longer if the PRA is greater than 80%. %African Americans make up 36% of the renal waiting list. However, they represent 31% of the unsensitized patients and 37% of the sensitized patients. The disparity in time to transplant is disproportionately larger when PRA is 80% or greater. This finding may be explained by the increased difficulty in finding a compatible donor in African Americans when a high level of matching is required. If the mean waiting time for unsensitized individuals is set at 1.00, the relative rate of transplant is affected similarly in Caucasians and Blacks when the PRA is 10–40% ( the rate of transplantation being approximately 70% that of unsensitized patients). However, with higher PRA values, African Americans are more adversely affected, with the rate of transplantation approaching only 40% of unsensitized Black recipients. At the time of re–listing, one can see a stepwise increase in sensitization to HLA with each HLA mismatch. African Americans, however, tend to become sensitized at a higher level than Caucasians, using the current algorithm. This may be due to mismatches in HLA–A (especially A2), which are not matched with the current algorithm. Once sensitized, African Americans are less likely to find a compatible donor. The use of CREG matching in the algorithm may help prevent sensitization and increase the chance of finding a suitable donor in patients already sensitized.