Cellular immune response of patients with uveitis to peptide M, a retinal S-antigen fragment.

Peptide M, an 18-amino acid fragment from position 303 to position 320 of retinal S-antigen, produces experimental autoimmune uveitis (EAU), similar to that produced by native S-antigen, in several vertebrate species including nonhuman primates. It was observed that 12 of the 39 (30.7%) patients with uveitis, 1 of the 29 (3.4%) patients with systemic connective tissue disorders (CTD) without eye involvement, 2 of the 7 (5.8%) patients of CTD with uveitis, 1 of the 17 (5.8%) patients with diabetic retinopathy, and none of the 19 normal healthy controls showed a significant lymphoproliferative response to peptide M (stimulation index of 3 or more). Yeast histone H3 peptide gave a positive response in 1 (2.5%), 2 (6.8%), 1 (14.2%), 2 (11.7%), and 2 (10.5%) individuals, respectively, in the different groups studied. In a few cases a positive response to yeast histone H3 peptide was observed without significant stimulation to peptide M. These findings indicate that peptide M could also be an immunogenic epitope of S-antigen in humans and be aetiopathologically related to uveitis in a subset of patients with this disease. However, unlike experimental animals, the responses to peptide M and yeast histone H3 were nonconcordant, necessitating further studies.