Proteomic surveillance of autoimmunity in Behcet's disease with uveitis: selenium binding protein is a novel autoantigen in Behcet's disease.

Autoimmune response to retinal antigens is considered to be one of the pathogenesis of uveitis in Behcet's disease (BD). In the present study, we comprehensively compared retinal autoantigens recognized by sera from BD patients with uveitis or healthy donors using proteomic technique, 2-dimensional electrophoresis (2DE) followed by Western blotting (WB). Six protein spots showing high reactivity with the serum from the BD patients were detected as candidate retinal autoantigens, and three of them were identified by mass spectrometry. Two of them were previously reported BD autoantigens, S-antigen and alpha-enolase, whereas the third one was selenium binding protein (SBP), a new candidate retinal autoantigen. Autoantigenicity of SBP was examined by WB and enzyme-linked immunosorbent assay (ELISA) using a recombinant protein. We found that 20 and 16% of the BD patients with uveitis were positive for the anti-SBP antibody by WB and ELISA, respectively. Comparison of clinical parameters between anti-SBP antibody-positive and -negative patients revealed that the anti-SBP antibody-positive patient group showed more frequent ocular inflammation than the antibody-negative patient group. Autoimmunity against the retinal SBP may contribute to the pathogenesis of uveitis in BD patients.