Corneal cells are known to participate in the regulation of local inflammatory processes by secretion of cytokines. As the corneal endothelium may be exposed to endotoxin in organ culture and endotoxin is known to trigger inflammatory reactions, we investigated the effect of endotoxin from E. coli on organ cultured donor corneae with respect to autocrine and paracrine functions and the endothelial viability and density. 6 pairs of donor corneae were transferred to organ culture. Medium samples were taken prospectively from day 0 to day 20. On day 10 the medium was changed and one of each pair was incubated with 50 micrograms/ml of endotoxin while the other was immersed in standard organ culture medium. The samples were screened for IL-1, -2, -4, -5, -6, -8, -10, TNF alpha and GM-CSF by ELISA. In addition endothelial cell counts were performed at day 0, after 10 and after 20 days of organ culture, using the fixed frame technique. All endotoxin-incubated organ culture media showed significantly increased IL-6 and -8 levels compared to the fellow cornea and to pre-exposure levels (P < or = 0.004). In the endotoxin-treated corneae a significantly higher endothelial cell loss occurred (P = 0.007) and signs of degeneration were observed. None of the other cytokines (IL-1 alpha, IL-2, IL-4, IL-5, IL-10, GM-CSF and TNF alpha) were detected during either the first (1 to 10-day) or the second (11 to 20-day) phase of incubation. A correlation seems to exist between an increase in IL-6 and -8 induced by endotoxin, and endothelial cell loss in organ culture.