Adverse immune reactions to gold in rheumatoid arthritis: lack of skin reactivity.

Adverse immune reactions develop in up to 30% of patients treated with gold compounds. However, sensitization to gold(I) drugs is rarely demonstrated by in vivo or in vitro testing. Recent data from a mouse model provides evidence that gold(I) is oxidized to gold(III) before T cells are sensitized. To study the diagnostic value of skin tests, patch testing with various gold compounds - including gold(I) and gold(III) - was performed in 50 patients with rheumatoid arthritis treated with gold(I) drugs. Positive patch test reactions to either gold(I) or gold(III) compounds were not detected. In contrast, the lymphocyte transformation test (LTT) revealed a gold(III)-induced response in one of the 7 patients being tested. We conclude that patch testing fails to indicate T cell sensitization to gold(I) drugs in rheumatoid arthritis patients. The in vitro response to gold(III) obtained by LTT supports the hypothesis that biooxidation of gold(I) compounds may play a crucial role for sensitization.