Immunogenetic and racial determinants of gold toxicity in rheumatoid arthritis.

Typing for antigens HLA-A,B,C and DR was performed on 165 rheumatoid arthritis patients (14 black, 151 white) who had received gold therapy to determine the relationship between HLA antigens and gold dermatitis, stomatitis, thrombocytopenia, and proteinuria. Dermatitis and stomatitis occurred in both black and white patients. Thrombocytopenia and proteinuria occurred only among the white patients studied. The absence of thrombocytopenia and proteinuria among the black patients was not statistically significant. Antigen HLA-DR7 was uncommon among black and white subjects with dermatitis (0 of 6 blacks, 4 of 48 whites), but this decrease in frequency was not statistically significant. Antigen HLA-DR3 was an important risk factor for thrombocytopenia (relative risk = 11.8, P = .0043) and proteinuria (RR = 5.8, P = .032). These results are consistent with previous studies of HLA-DR3 and gold toxicity. The only black patient with stomatitis possessed the A1B8DR3 phenotype. Future studies should examine whether the same HLA antigen confers risk of different gold toxicities in different racial groups, and whether there are HLA antigens that provide a protective effect.