A significant increase of HLA-DR3 and DR2 in systemic lupus erythematosus among blacks.

We found a highly significant increase in the incidence of HLA-DR3 and DR2 antigens in black patients with systemic lupus erythematosus (SLE). HLA-DR3 was found in 62% of patients and 20% of controls (p less than 0.0001), and DR2 in 41% of patients and 18% of controls (p less than 0.001). The relative risk (RR), conferred by DR3 was 6.41, and that by DR2 was 3.03. Further, 84% of the patients had DR3 and/or DR2; the combined RR for SLE with these antigens was 9.0. A significant proportion of the patients (57%) developed lymphocytotoxic antibodies; of these, 19% had HLA specific antibodies.