Hypersensitivity to gold in gold sodium thiomalate-induced dermatosis.

Gold compounds are widely used in the treatment of rheumatoid arthritis. Mucocutaneous side-effects leading to the discontinuation of medication are common with these drugs. We investigated whether allergic mechanisms are involved in dermatosis induced by gold sodium thiomalate (GSTM). Thirteen gold dermatosis patients, 15 arthritis patients without any side-effects from GSTM and 11 healthy controls participated in the study. Venous blood lymphocytes from these subjects were cultured with GSTM and gold sodium thiosulphate (GSTS) in the lymphocyte proliferation test (LPT). In some cases, interferon-gamma-producing cells were enumerated in vitro (T-cell ELISpot). The subjects were also patch-tested with GSTM and GSTS. The LPT to either GSTM, GSTS or both was positive in 12 of 13 patients with gold dermatosis. In the arthritis patient group without side-effects from gold, the LPT gave two false-positive results and in the healthy control group the LPT was falsely positive with one subject. T-cell ELISpot was positive in four of six gold dermatosis patients and negative in the arthritis and healthy control groups. Only one patient who also developed contact dermatitis from gold jewellery was positive to gold in the patch test. These results indicate that gold dermatosis is mediated, at least in part, by allergic mechanisms and that the LPT is of value in the diagnosis of gold dermatosis.