Thalidomide activity in experimental Arthus and anaphylactic reactions.

Lepra reaction is characterized by erythema nodosum leprosum (ENL) fever, lymphadenopathy, neuritis, arthralgia, and other symptoms which constitute a serious clinical aspect of the disease in many patients with lepromatous leprosy. These reactions, though sometimes present in untreated leprosy, usually occur during the eourse of treatment with sulfones, when the Morphologic Index (MI) indicates that the number of viable bacteria is low (10). The etiology of these reactions has never been adequately demonstrated, but it has been proposed that these are perhaps reactions to immediate hypersensitivity, similar to Arthus or serum-sickness reactions, occurring when the bacilli or their degradative products are liberated, combine with circulating antibody, and fix complement (14.lO) . Following the work of Sheskin in 1965 (13), numerous authors have demonstrated the extraordinary efficacy of thalidomide in the alleviation of the reaetional symptoms of leprosy. The mechanism by which this drug acts in the lepra reaction is unknown. The suggestion that the teratogenic effect of thalidomide might in part be based on the suppression of the immune response has stimulated a number of investigatIons concerning its effect in skin-graft rejection and antibody production (5, 6), and a brief report on its effect on delayed and immediate hypersensitivities (9). Most of these reports indicate that its role in modifying