COP-1 is one of a series of polypeptide preparations developed to stimulate myelin basic protein (MBP), a natural component of the myelin sheath. MBP in Freund's complete adjuvant induces experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). In saline, MBP suppresses EAE. This is the rationale for the use of COP-1 in MS.