Studies on levamisole, a potentially useful drug in the treatment of Behçet's syndrome

The anthelmintic drug, levamisole, was shown to amplify the response of human peripheral blood lymphocytes to vegetable mitogens. A similar enhancement of blast formation in the mixed lymphocyte culture was also demonstrated. High concentrations of the drug led to depression of both of these responses. These observations led to studies in a rat breast cancer model in which immunopotentiation was demonstrated in vivo, and this effect was associated with tumor regression. As in the human in vitro studies, high doses of the drug were not associated with augmentation of the immune response and in this circumstance no inhibition of tumor growth was observed. Assuming that potentiation of immune responsiveness is of benefit to patients suffering from Behçet's syndrome, the development of clinical trials employing levamisole appears justified, as long as the drug dosage is carefully monitored.