The purpose of this paper was to examine whether closer HLA matching of kidneys for transplant is achieved when the patient and donor are of the same racial group.

Data for this study were derived from HLA phenotyping data in the computer registry at the Regional Organ Bank of Illinois. Specifically, HLA data was selected for potential recipients on the Illinois cadaver renal transplant waiting list in August 1990 and donors for the period from 1988 to 1990. Data were also utilized for 448 consecutive cadaver renal transplants performed at six transplant centers from March 1989 through December 1990.

The waiting list was 41% black and 59% non-black. This was similar to the racial distribution of recipients: of whom 38% were black and 62% non-black. However, 17.9% of the transplanted kidneys originated from black donors, and 82.1% from non-black donors. Thus, most of the transplanted kidneys for both black and non-black patients came from non-black donors: 75% of the black recipients and 86% of the white recipients received kidneys from non-black donors. (The authors cross-tabulated the donor race by recipient race for each of the four HLA-mismatch categories and reported statistical significance tests for several of these comparisons.)

Briefly, only three blacks received zero HLA-A, B, DR mismatch transplants (2%) compared with 21 non-blacks (8%). There was a total of 64 “well-matched” (zero-HLA-A, B, DR mismatch; zero-HLA-A,B mismatch; zero HLA-B, DR mismatch; or 1 HLA-A, B, DR mismatch) transplants. Of the 60 transplants from black donors, 5 (6%) were “well-matched,” and 100% went to black recipients. Of the 368 transplants from non-black donors, 59 (16%) were “well matched,” and 86% went to non-black recipients.

Of the 170 transplants to black recipients, 13 (8%) were well-matched; 42 transplants were from black donors, of which 12% were well-matched; and 128 transplants were from non-black donors, of which 6% were well-matched. Of the 278 transplants to non-black recipients, 51(18%) were well-matched;:240 transplants were from non-black donors, of which 21% were well-matched; 38 transplants were from black donors; and none were well-matched.

These data show that the best HLA matches from both blacks and non-blacks were derived from donors of the same racial group as the recipient. Additionally, mismatches were most likely when the cadaver donor-recipient pairs were of different races.

The authors attribute this finding to HLA frequency differences between blacks and Caucasians. The HLA frequencies from blacks and Caucasians on the renal transplant waiting list and donors were compared. The HLA phenotype frequencies within each race were similar in the waiting list and the donor populations. However the HLA frequencies between blacks and Caucasians differed substantially. (The authors presented numerous comparisons of various combinations of HLA categories.)

Additionally, kidneys from non-black donors were rarely given to blacks with HLA phenotypes unique to or more common in blacks.

The authors conclude that a larger number of black donors is needed to improve the quality of HLA matching for potential black kidney transplant recipients.