Suppression of experimental allergic encephalomyelitis by EN3638: dependence on adjuvants and treatment schedules.

Oral administration of 2, 3 or 4 doses of 100 or 250 mg/kg of EN3638 during the incubation period of experimental allergic encephalomyelitis delayed the onset and reduced the incidence and severity of clinical signs and histological lesions. Five doses of 50 or 100 mg/kg effected virtually complete and permanent suppression of clinical signs even after cessation of therapy, and five doses of 250 mg/kg eliminated histological lesions as well. Optimum results required coverage of the entire incubation period regardless of dose level. These results were obtained only when carbonyl iron was used as the adjuvant for production of EAE. When complete Freund's adjuvant was used, EN3638 delayed the onset but had little or no influence on late-developing clinical signs and histologic lesions after cessation of therapy. The permanence of suppression when carbonyl iron was used is related to the absence of an oil depot. Carbonyl iron is a superior adjuvant for drug suppression studies.