Background: Scleritis can be a destructive disease frequently associated with autoimmune disorders. It is believed that primary vasculitis plays an important role in its pathogenesis, but little is known about the cellular effector mechanisms. The purpose of this study was to analyze the inflammatory cellular infiltrate in scleritis.
Patients and methods: Two enucleated eyes were studied. In one patient, enucleation was done after perforation occurred in anterior necrotizing scleritis and, in the other, after the misdiagnosis of posterior scleritis as an intraocular tumor. Morphological criteria and immunohistochemical methods were used to characterize the inflammatory cellular infiltrate.
Results: The cells infiltrating the scleral fibers in the enucleated eyes consisted predominantly of T cells in both cases; many of the T cells were CD4-positive. Clusters of B cells were found in perivascular areas. In circumscribed areas neutrophils, macrophages, and plasma cells were part of the scleral infiltrate. Signs of a granulomatous process with activated macrophages (epitheloid and giant cells) were present in necrotizing scleritis. Expression of major histocompatibility class II molecules (MHC II) was found on lymphocytes and rarely on macrophages. Signs of primary vasculitis were not found in any of the specimens.
Conclusion: The cellular infiltrate in scleritis shows, at least at certain stages, features compatible with a T-cell mediated (autoimmune) disorder, which has major therapeutic implications.