HIGH RESOLUTION HLA-DR TYPING OF AFRICAN-AMERICAN AND NON-AFRICAN-AMERICAN RENAL ALLOGRAFT DONOR AND RECIPIENT PAIRS.
Ian S Gourley1, Harold I Feldman2, Jane D Kearns1, Steve Birkos1, Scott E Aikey1, Eileen Burns2, Marshall Joffe2, and Malek Kamoun1, Departments of Pathology and Laboratory Medicine1 and Epidemiology and Biostatistics2, Hospital of the University of Pennsylvania, Philadelphia, PA.

African-American (AA) renal transplant recipients have been observed to have an increased risk of rejection and allograft loss. To investigate this phenomenon, high resolution (HR) HLA-DR typing was performed by SSP-PCR on recipient/donor pairings in which HLA-DR alleles had originally been typed to low resolution (LR) by serology or SSP. HR typing was carried out on 149 of 210 recipient/donor pairs, but was not indicated in 61 cases in which there were no potential mismatches (MM) to explore.

Fifteen cases have been excluded from analysis because the DR type could not be resolved by SSP-PCR. The results for the remaining patients are shown.
 

DR Antigen MM
Low-res, all patients
High-res, all patients
Low-res, AA
High-res, AA
Low-res, non-AA
High-res, 

non-AA
0
50
26
8
4
42
22
1
108
98
30
18
78
80
2
37
71
10
26
27
45
n
195
195
48
48
147
147
% patients MM
76%
87%
83%
92%
71%%
85%
% alleles MM
47%
62%
54%
73%
45%
58%
 
High resolution typing was 1.7 times more likely to discover additional MM in AA subjects than non-AA subjects (95% confidence interval 1.1-2.5, p=0.02, Fisher’s exact test). The DR subtypes most frequently MM after HR typing in non-AA subjects were DR*04 (53%) and DR*11 (18%), while in AA subjects they were DR*13 (25%) and DR*15 (35%).

In conclusion, this study shows that AA are more likely than non-AA to be HLA-DR mismatched with their donors after LR typing, and that the degree of HLA-DR MM increases disproportionately in AA after HR typing. Furthermore, the distribution of alleles MM after high resolution typing differs between AA and non-AA.