IL-8 GENE-EXPRESSION IN CULTURES OF HUMAN CORNEAL EPITHELIAL-CELLS AND KERATOCYTES

Purpose. To determine if human corneal keratocytes and epithelial cell s synthesize and release IL-8 after stimulation with selected proinfla mmatory cytokines. Methods. Human corneal keratocytes and epithelial c ells were isolated from human corneal buttons and grown independently in vitro. Epithelial cell cultures stained positive in immunofluoresce nt tests with antibody specific for keratin (AE1/AE3), whereas keratoc yte cultures were unreactive. Both cell types reacted with anti-viment in antibody. Cultures of the two cell types were treated with various concentrations of human recombinant interleukin-1 alpha or TNF-alpha. Culture supernatants were then assayed at timed intervals by enzyme-li nked immunosorbent assay for IL-8 content. Cytokine mRNA levels in cel l lysates were monitored by Northern blot analysis. Results. Exposure of corneal keratocytes and epithelial cells to either interleukin-1 al pha or TNF-alpha stimulated IL-8 mRNA synthesis and IL-8 production in a dose-response fashion. It was also found that TNF-alpha stimulated the synthesis of comparable amounts of IL-8 in both cell types. Howeve r, when IL-8 synthesis between the two cell types was compared after i nterleukin-1 alpha stimulation it was found that keratocytes synthesiz ed 33 times more IL-8 than did epithelial cells. Conclusions. The resu lts establish that pro-inflammatory cytokines can induce IL-8 synthesi s in both human corneal epithelial cells and human corneal keratocytes . They also suggest that interleukin-1 alpha may play a more active ro le in amplifying inflammatory responses in the stroma than in the epit helial layer of the cornea.