IL-4 regulates chemokine production induced by TNF-α in keratocytes and corneal epithelial cells

Background - Eosinophils are thought to play a major role in the pathogenesis of corneal lesions in ocular allergies. The regulation of chemokine production in corneal cells by the Th2 cytokine, interleukin 4 (IL-4), was examined in order to investigate its role in ocular allergies. Methods - Pure cultures of human corneal epithelial cells and keratocytes were exposed to tumour necrosis factor α (TNF-α) and/or IL-4. 24 hours after exposure, culture supernatants were removed and concentrations of IL-8 and RANTES were quantified by ELISA assay. Results - Simultaneous addition of IL-4 inhibited TNF-α induced IL-8 production in both corneal epithelial cells and keratocytes. TNF-α and IL-4 synergistically stimulated the production of RANTES in keratocytes. Conclusion - Differential regulation of chemokine production from corneal cells by IL-4 may play a role in the selective recruitment of predominantly eosinophils to the ocular surface in ocular allergies.