Lymphocyte transformation and the effect of circulating immune complexes in humans with syphilis

Peripheral blood lymphocytes and serum obtained from patients with secondary syphilis were studied in vitro by the technique of lymphocyte transformation. The sera from these patients also were examined for circulating immune complexes by the method of precipitation with polyethyene glycol. The lymphocytes responded poorly to in vitro stimulation with mitogens and treponemal antigens. In addition, the lymphocyte responses were poorer in autologous syphilitic serum than in normal human serum. The serum from some patients with syphilis contained circulating immune complexes that were present during infection, and decreased in amount after treatment with penicillin. In general, lymphocyte responses to mitogen and antigen were greater after therapy.