PRODUCTION OF INTERLEUKIN-6 AND GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR BY MURINE IRIS AND CILIARY BODY EXPLANTS

Purpose. To examine the ability of murine iris-ciliary body explants to produce cytokines with proinflammatory activities. Methods. Supernatants derived from murine iris-ciliary body (I-CB) tissue explants cultured (four per well in 1 ml medium) in the presence of indomethacin were analyzed for the production of IL-1, IL-2, IL-3, IL-6, tumor necrosis factor-alpha/beta (TNF alpha/beta) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Analysis was performed by thymocyte costimulation, growth factor-dependent cell proliferation, TGF-beta-sensitive mink lung epithelial cell proliferation, and enzyme-linked immunosorbent assays (ELISA). Results. Supernatants from I-CB explants cultured in vitro for 24 hours contained significant thymocyte costimulatory activity. This activity was fully neutralized by a combination of antisera to IL-1 and IL-6, and ELISA analysis confirmed that IL-6 was a significant component of the supernatant (402.1 pg/ml). TNF alpha/beta were also found in low concentrations (similar to 2.0 U/ml) by ELISA analysis, whereas IL-2 and IL-4 were not detectable. Significant amounts of GM-CSF (15.8 U/ml), but no IL-3, were detected. Conclusions. These results demonstrate that normal I-CB tissue contains cells capable of producing IL-6, GM-CSF, and IL-1. Because of the proinflammatory nature of IL-6 and IL 1, and the ability of GM-CSF, IL-1, and IL-6 to enhance functional capabilities of antigen presenting cells, regulation of the production of these cytokines may contribute significantly to the maintenance of the immunologic status of this regional site.