Cross‐reactivity between an HLA‐B27‐derived peptide and a retinal autoantigen peptide: a clue to major histocompatibility complex association with autoimmune disease

Statistical correlations between the expression of various HLA antigens and certain autoimmune diseases have been observed for both HLA class I and II antigens. Autoimmune diseases like spondyloarthropathies and anterior uveitis are associated with HLA‐B27, but uveitis in Behçet's disease with HLA‐B51. We describe a peptide from disease‐associated HLA class I antigens sharing sequence homologies with a highly uveitogenic epitope from the retinal autoantigen S‐antigen. S‐antigen induces autoimmune uveitis in the animal model and is a major autoantigen in human disease. The HLA peptide induced uveitis in the Lewis rat and, moreover, suppressed S‐antigen‐induced disease when administered orally. Patients' PBL cross‐reacted with the HLA‐ and corresponding retinal peptide, explaining the organ specificity of the disease.