SUPPRESSION OF EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS IN THE LEWIS RAT, BY ADMINISTRATION OF AN ACYLATED SYNTHETIC PEPTIDE OF MYELIN BASIC-PROTEIN

A Myelin Basic Protein (MBP) epitope encephalitogenic for the Lewis ra t (amino acid residues 68-86) was synthesized and acylated by the atta chment of a palmitoyl residue. Lewis rats treated intravenously (i.v.) with the palmitoylated peptide alone were better protected against cl inical manifestations of experimental allergic encephalomyelitis (EAE) than rats treated with the peptide inserted into liposomes or with th e native peptide at similar doses. The administration of the acylated peptide (PAL68 86) conferred excellent protection against a challenge with the encephalitogenic peptide (p68-86) or with the intact MBP mole cule, both before and after induction of active disease, and also when administered to recipients after the transfer of lymphocytes from MBP -challenged donors. Histological manifestations were also reduced to a statistically significant degree. Treatment with a palmitoylated pept ide from a non-encephalitogenic region of the MBP molecule (PAL44-62) or with a palmitoylated unrelated peptide were ineffective. In vitro A g-specific proliferative responses as well as the ability to transfer disease to syngeneic recipients, by lymph node lymphocytes from PAL68- 86-treated donors, were considerably reduced. Addition of IL-2 to thes e cultures failed to restore either Ag-specific responsiveness or the ability of the cells to transfer disease. The results suggest that the administration of acylated peptides induces a profound state of unres ponsiveness, and thus may provide an effective means for treating T ce ll-mediated autoimmune inflammatory disorders.