Phage Immunoprecipitation Sequencing of Autoantigens in Autoimmune Retinopathy.

PURPOSE: To identify autoantigens in autoimmune retinopathy patients by phage immunoprecipitation sequencing (PhIP-Seq), a new technique for autoantigen discovery.

METHODS: PhIP-Seq was used to sequence putative autoantibodies in plasma from 11 patients with autoimmune retinopathy and eight controls. We compared the autoantibodies' molecular weights with those of proteins detected by Western blot.

RESULTS: Several autoantigens were found in cases and not detected in the controls. Autoantigens RTN3, PRPF6, TRPC6, and B3GNT8, four proteins expressed in the retina, were detected in plasma as autoantibodies from one patient each and no controls. Only one patient had an autoantibody, B3GNT8 (43.4 kDa), within a similar weight range as that detected by antiretinal antibody Western blot (42 kDa). Autoantibody POLR3A, which has a well-characterized role in scleroderma, was detected in two cases and no controls.

CONCLUSION: PhIP-Seq detected autoantigens that are expressed in the retina as well as scleroderma-related autoantigens in autoimmune retinopathy patients.