Levamisole-induced hypersensitivity.

A 73-year-old woman with rheumatoid arthritis was treated with Levamisole, 150 mg per day, on 2 days a week. Her arthritis improved, but she developed a severely itching rash, and the treatment was stopped after 6 months. Penicillamine was subsequently given and tolerated without skin complications. 15 months after regular Levamisole was stopped, she was given a single dose of 150 mg which provoked fever of 40 degrees C and rash. Thirteen punch-biopsy specimens were examined by direct immunofluorescence microscopy. During the Levamisole treatment, granular deposits of IgG and C3 were found at the dermal--epidermal junction. Subsequently, the deposits disappeared, but reappeared after Levamisole challenge. The patient's leukocytes were exposed in vitro to Levamisole, and 36% of the total histamine content in the basophils was released. Our results provide further evidence that Levamisole can cause type-I as well as type-III hypersensitivity.