Effect of thalidomide on induction of antibody synthesis in mice to the T-independent antigen, DNP-Ficoll.

Since 1 965 , thal idomide has been used in a l leviat ing the signs and symptoms of a major medical complicat ion of lepromatous leprosy, erythema nodosum lepro­ sum (EN L) . I H istologically, the hal lmarks of E N L lesions are vascul i t i s or vascular necrosis , oedema and inflammation with infil trates of neutrophi l s affect ing the entire dermis and subcutaneous fat . 2 The factor or factors that trigger the influx of neutrophi ls i s unknown . For thal idomide to be effect ive in ENL, i t m ust in terfere with one or more of the essent ia l s teps in the pathogenesis of this syndrome. Since i t has been suggested that EN L is an immune complex mediated disease,3 , 4 we have investigated the effect of thal idomide on h umoral immunolo­ gical responses . Thalidomide significantly i nhibits an IgM but · not an I gG response in mice to the T-cel l -dependent antigen, sheep erythrocytes; it also selectively decreases serum IgM concentrat ions among leprosy patients being treated for their ENL. 5 These observations have prompted us to speculate that a c l in ical ly relevant site of action for thal idomide in ENL is on the synthesis of IgM antibody. I f thal idomide acts on immunocompetent cel ls , the cell target of the drug must be among the macrophage, IgM antibody forming B cell and helper or suppressor lymphocytes .