HLA, blood groups and secretor status in patients with established rheumatic fever and rheumatic heart disease.

The distribution of HLA-A, -B and -DR antigens as well as blood groups and secretor status was studied in sporadic, North Indian patients of rheumatic fever and rheumatic heart disease. While HLA-Aw33 occurred with an increased frequency in the patient group (X2 = 4.01), no statistically significant differences were observed in the frequency of B-locus antigens. In the DR locus, HLA-DR3 was found to be significantly increased (50% vs 26.1%, X2 = 13.8) and DR2 significantly reduced (21.8% vs 47.0%, X2 = 15.6). Also, there was a preponderance of non-'O' blood group individuals in the patient group as compared to controls. The DR3 association was significant only in those patients of RHD who did not have any previous history of rheumatic fever. These results indicate that susceptibility to rheumatic heart disease is HLA-class II mediated, with HLA-DR3 influencing susceptibility and DR2 conferring protection.