HLA antigens and lymphocytes in proliferative vitreoretinopathy

An immunohistopathological study was performed on 33 epiretinal membrane specimens obtained during vitreoretinal surgery from patients with rhegmatogenous retinal detachment complicated with proliferative vitreoretinopathy (PVR). Immunofluorescence and immunoperoxidase methods were used to detect major histocompatibility complex or HLA antigens and immunocompetent cells, and to identify the cellular and the extracellular component of the proliferative tissue. The following antigens were detected in epiretinal membranes: cytokeratin in 18 (of 18 cases studied for this antigen), glial fibrillary acidic protein in 20 (of 20), vimentin in 20 (of 20), actin in 16 (of 18), fibronectin in 20 (of 20), macrophage CD68 in 16 (of 18), leukocyte common antigen in 12 (of 18), T-cell CD45R in 13 (of 22), HLA-ABC in 27 (of 33), HLA-DR in all the 33 membranes and HLA-DR alpha chain in 32 of 33 membranes. We observed the presence of macrophages and of an activated T-cell population in PVR membranes. HLA-DR antigen expression was found on pigmented and nonpigmented epithelial cells and on mononuclear cells in all epiretinal membranes. The HLA-DR expression on retinal pigmented epithelial cells could play a role in triggering a local immune response in PVR. These findings suggest the involvement of immunological phenomena and probable interactions between the immune system and peptide growth factors.