Oligopeptides of three to five residues derived from uveitopathogenic sites of retinal s-antigen induce experimental autoimmune uveitis (EAU) in lewis rats

We have previously reported that microbial peptides having 3 to 6 amino acid sequence homology with uveitopathogenic peptide of retinal S-antigen (S-Ag) are capable of inducing experimental autoimmune uveitis (EAU) in Lewis rats and subhuman primates. T-cells obtained from animals immunized with these microbial peptides proliferate when stimulated with S-Ag peptide in culture and vice versa. We were interested to know whether these 3 to 6 identical amino acid residues by themselves were sufficient to induce EAU in susceptible animals under optimal conditions. For this purpose we have determined the response of synthetic oligopeptides of 3 to 18 amino acid residues for their ability to indice EAU. Here, we report that small synthetic oligopeptides of 3 to 5 amino acid residues of the two uveitopathogenic peptides of S-Ag induced EAU in Lewis rats, although with a higher dose (2000 μg/rat) than that of the larger peptides (50 μg/rat). These results define the core sequences in the uveitopathogenic peptides of retinal S-Ag.