[Human corneal epithelial, stromal and endothelial cells produce interleukin-6]

We have been investigating the production of cytokines in ocular tissues. In this paper, we demonstrated the in vitro production of interleukin-6 (IL-6) by human corneal epithelial, stromal and endothelial cells using enzyme-linked immunosorbent assay (ELISA). In culture supernatant of the stromal cells, the production of immunoreactive IL-6 was induced, depending upon the doses of lipopolysaccharide (LPS) or IL-1 alpha added into the culture. Detectable IL-6 activity in the supernatant of the stromal cells was found 2 hours after addition of IL-1 alpha and the activity increased to a peak level at 48 hours. On the other hand, in the supernatant of the endothelial cells, IL-6 activity was found even in unstimulated-culture, and induced further by LPS stimulation. The molecular weights (MWs) of the IL-6 produced by the epithelial, stromal and endothelial cells were calculated by gel filtration as about 30 kDa. From Western blotting analysis, the MW of IL-6 produced by the stromal cells was also determined to be 30 kDa.