Lymphocyte responses to peptide M and to retinal S-antigen in uveitis patients

A synthetic amino acid, peptide M18 (18 Amino acids in length which correspond to the amino acid positions 303-322 of bovine S-antigen: DTNLASSTIIKEGIDKTV), is capable of inducing experimental autoimmune uveitis in monkeys and Hartley guinea pigs as well as Lewis rats. Recently, the amino acid sequence of human S-antigen corresponding to peptide M was found to be virtually identical to that of bovine S-antigen. To investigate the role of the epitope corresponding to peptide M in human uveitis, 21 patients with uveitis were tested for proliferation of peripheral mononuclear cells against peptide M18 and bovine S-antigen. Six of the 21 patients responded to S-antigen and 4 of these 6 patients responded to peptide M18. These findings show that peptide M18 is immunogenic in man and provide additional support to the hypothesis that the amino acid sequence which corresponds to peptide M might be involved in uveitic conditions in man.