Immunochemical studies of epiretinal membranes using APAAP complexes: evidence for macrophage involvement in traumatic proliferative vitreoretinopathy.

Proliferative vitreoretinopathy is characterized by cellular proliferations in the periretinal space resulting in traction retinal detachment. Numerous cellular elements and connective tissue components have been identified by morphologic criteria as well as immunochemical techniques. In this study, we used the recently introduced APAAP (alkaline phosphatase - anti-alkaline phosphatase) immunostaining procedure to identify macrophages, T-lymphocytes, the structural proteins fibronectin, vimentin, and cytokeratin, and a proliferating cell antigen, in eleven human epiretinal membranes obtained during vitreoretinal surgery. Our results confirm that the pathologic processes in PVR are not immunologically mediated, but reveal the features of physiologic wound healing and scar formation. Posttraumatic PVR seems to be characterized by a severe initial inflammatory reaction as evidenced by the presence of numerous macrophages, whereas idiopathic PVR, as a complication of retinal detachment, may be caused by different mechanisms in the early pathogenesis.