MHC CLASS-II ANTIGEN EXPRESSION BY OCULAR CELLS IN PROLIFERATIVE DIABETIC-RETINOPATHY

An immunohistological study was performed on ciliary biopsies of the p ars plana obtained surgically in 10 patients suffering from diabetic r etinopathy and on 15 surgical specimens of pre-retinal neovascularized membranes. Using immunofluorescence and immunoperoxidase procedures, linear deposits of IgG, IgA and complement components were found in th e 8 pars plana from patients with proliferative diabetic retinopathy, at the basal pole of the pigment epithelial cells and within the strom a. In contrast, these deposits were absent from normal pars plana and from the cases of background retinopathy. Moreover, pigment and non-pi gment epithelial cells were found to express HLA DR and DQ determinant s, in six of the eight patients with proliferative retinopathy. Immuno histological examination of pre-retinal membranes showed deposition of immunoglobulins and complement components within the connective strom a and along the new blood vessels. Endothelial cells of the newly form ed vascular walls strongly expressed class II antigens on their membra ne, as well as scattered stromal cells. As neither pigment epithelial cells nor retinal vascular endothelial cells normally express class II determinants, our results suggest the involvement of immunological ph enomena in intraocular proliferative diseases and eventual interaction s between the immune system and peptide growth factors. However, wheth er or not this immune reaction plays a role in the initiation or exten sion of intra-ocular proliferation remains to be determined.