Studies of Cyclophosphamide Suppression of Experimental Allergic Encephalomyelitis in Wistar Rats

Experimental allergic encephalomyelitis (EAE) is completely inhibited in Wistar rats sensitized to spinal cord-adjuvant and treated with cyclophosphamide (CY) in doses of 5, 10 or 12 mg/kg from the day of sensitization through the 17th post-sensitization day. Such animals develop neither clinical neurologic signs nor histologic evidence of the disease. Furthermore, production of complement-fixing antibrain antibody is suppressed. Comparable inhibitory effects can be obtained by a single dose of CY of 100 mg/kg given 2 days after sensitization. Inhibition of EAE extends for at least 112 days after stopping CY. Limited “break-through” occurs in some rats re-sensitized to spinal cord by a different route after prior CY treatment. Evidence favoring the thesis that CY exerts its striking inhibitory action on this auto-immune disease through immunologic mechanism(s) is presented.