Proliferative diabetic retinopathy with lymphocyte-rich epiretinal membrane associated with poor visual prognosis

The aim of this study was to analyze lymphocyte infiltration using immunohistochemistry in proliferative diabetic retinopathy (PDR) membranes.

Sixteen patients, 13 with PDR and 3 without diabetes, underwent pars plana vitrectomy, and the epiretinal membrane was peeled. Formalin-fixed, paraffin-embedded epiretinal membrane tissues were processed for immunohistochemistry with anti-leukocyte common antigen (LCA), CD3, and CD20 antibodies. Lymphocyte density was determined by direct counting at a high magnification under a light microscope, which was compared with the patients' visual prognoses.

The lymphocyte density ranged from 1 to 52 (mean, 9.5) in high-power fields. Of 13 membranes, 5 showed a lymphocyte density of >5 cells, whereas the other 8 membranes showed a cell number of <2. The former type is defined as a lymphocyte-rich epiretinal membrane (LERM). Infiltrated lymphocytes were immunohistochemically positive for CD3, a T-cell marker, but not for CD20, a B-cell marker. All patients with LERM had poor visual prognosis after vitrectomy. In contrast, the visual prognosis in 7 patients with non-LERM improved or remained unchanged. A significant association was observed between high-level lymphocyte infiltration in the epiretinal membrane and poor visual prognosis (P < 0.001). LCA(+) mononuclear cells were not observed in epiretinal membranes in the absence of diabetes.

These results suggest that the high-level infiltration of T lymphocytes into the PDR membrane is well correlated with poor visual prognosis. Histopathologic observation of the epiretinal membrane in patients with PDR may provide significant prognostic information.