Molecular requirements involved in suppression of eae by synthetic basic copolymers of amino acids

Abstract A survey was carried out in order to characterize the molecular requirements involved in suppression of experimental allergic encephalomyelitis (EAE ∗ ) by synthetic basic copolymers. A copolymer identical in composition to the most active suppressive copolymer (denoted Cop 1) was prepared from amino acids of D configuration. This material has no suppressive effect on EAE thus eliminating the possibility that the biological activity of the copolymers is due to their basicity either as regards net electrical charge or distribution of the charge on the molecule. On the other hand, a related copolymer in which tryptophan replaces tyrosine (Cop 4) was very effective in disease suppression. Cop 4 manifests at least the same extent of cross-reactivity with the natural encephalitogen as Cop 1, both in vivo and in vitro , whereas D -Cop 1 is not cross-reactive. These findings support the hypothesis that immunological mechanisms are involved in the suppressive phenomenon.