Ocular pANCA antigens are expressed in nonpigmented ciliary body epithelium and are conserved in multiple mammalian species

Abstract

PURPOSE: pANCA marker autoantibody is expressed by a subset of patients with anterior uveitis. A recombinantly isolated pANCA monoclonal antibody, Fab 5–3, identifies ocular expression of corresponding pANCA antigens in human ciliary body and retina. In this study, Fab 5–3 was used to explore pANCA antigen expression in ocular tissues of multiple mammalian species and identify the ciliary body cell type expressing the pANCA antigen. METHODS: Ocular tissues were obtained from several mammalian species and evaluated for expression of the pANCA (Fab 5–3) antigen(s) using immunohistochemistry and Western analysis of tissue extracts. Additionally, primary cultures of nonpigmented and pigmented rabbit ciliary body epithelium were analyzed for pANCA expression using immunofluorescence and Western analysis. RESULTS: Ocular pANCA (Fab 5–3) antigen expression was observed by immunohistochemistry only in the cytoplasm of retinal ganglion cells and ciliary body epithelium. Retinal antigen expression was conserved in all species examined. Ciliary body expression was observed in human, rabbit, rat, and mouse, but not in pig or cow. Antigen expression in the rabbit ciliary body was restricted to the nonpigmented layer as defined in primary cultures of nonpigmented and pigmented ciliary body epithelium. Immunoreactive proteins in both the human and rabbit included a 32–33 kDa doublet (histone H1), and novel 80 and 100 kDa proteins. CONCLUSIONS: This study identifies ocular pANCA antigen expression in multiple mammalian species localized to the retinal ganglion cell layer and the non-pigmented ciliary body epithelium. The present study also establishes novel 80 and 100 kDa proteins which may correspond to the cytoplasmic antigens detected in situ and can be further characterized biochemically and immunologically using small animal model systems.