DR antigens and gold toxicity in white rheumatoid arthritis patients.

An increase in the frequency of DR3 in rheumatoid arthritis (RA) patients exhibiting toxic reactions to chrysotherapy has been reported in several studies of white patients. This study was designed to compare DR antigen frequencies in local white RA patients undergoing chrysotherapy with their response to treatment. The results from our sample of RA patients (n = 148) confirm the fact that there is increased frequency of DR3 in patients who develop toxic reactions to gold therapy, as reported in other studies of white patients. The DR3 increase was attributable to those gold-treated patients who developed proteinuria, and was not observed in patients who developed skin toxicity. Interestingly, the associations were not as strong as those found in other reports. Only 21.1% of the patients with DR3 manifested toxic reactions overall, with only one-third of the patients with proteinuria being DR3 positive. There was also an association of toxicity, albeit not significant, with a decreased frequency of DR2, which is consistent with the suggestion that this phenotype may protect against adverse reactions to gold treatment. These results suggest that while DR3 is significantly associated with adverse response to gold treatment, the relationship is not as strong as that previously reported. Explanation of these differences remains to be elucidated.