The basic copolymer of alanine, glutamic acid, lysine and tyrosine, denoted Cop 1, is an efficient suppressor of experimental allergic encephalomyelitis (EAE) induced with the bovine basic encephalitogen in guinea pigs and rabbits. The suppression was very effective also when the experimental disease was induced with the basic protein from human source. Two related polymers, one in which glutamic acid was replaced with aspartic acid, and one devoid of tyrosine, were less effective in the suppression of the experimentally induced disease.

The route of administration of Cop 1 plays an important role in its suppressive effectiveness, with intravenous injections being the most efficient. The injection schedule and dose of injection are also of great importance; thus, repeated doses of Cop 1 starting five days after the administration of the basic protein are suppressive, whereas a single dose of 5 mg given 72 h after challenging with the basic protein does not suppress EAE. Cop 1 is not a nonspecific immunosuppressant, as it does not affect the immune response towards a variety of antigens, including the rejection of a skin graft.

When EAE was induced with the human encephalitogen, the histological changes observed included demyelination and fibrosis in the guinea pig brain.