Cytokine regulation of human corneal epithelial cell ICAM-1 (CD54) expression

Purpose. To determine if Intercellular Adhesion Molecule-1 (ICAM-1; CD54) plays a role in the attachment of eosinophils to the cornea during inflammation associated with severe ocular allergy, we investigated whether proinflammatory cytokines could regulate ICAM-1 protein expression on cultured primary human corneal epithelial cells (HCEs). Methods. HCEs were obtained by trypsin/pronase digestion of human corneas (Lions Eye Bank, Houston & San Antonio, TX) and cultured in keratinocyte growth medium. HCEs were grown to confluency in either culture flasks or 96-well plates, then treated with various concentrations of Interferon-γ (IFN-γ 1-500U/ml) or Interleukin-1α (IL-1α; 0.001-10ng/ml) for various times. The cells were then washed in PBS and fixed in 1% paraformaldehyde in PBS. ICAM-1 expression was measured using FACS analysis and a cell-based ELISA assay using a monoclonal mouse anti-human ICAM-1 antibody. Results. IFN-γ induced a dose and time dependent increase in ICAM-1 expression. Maximal expression was seen at 50U/ml using both FACS analysis and the ELISA. ICAM-1 expression increased 20-fold over control values. No change in ICAM-1 expression could be detected after IL-1α treatment with either technique. Conclusions. We demonstrate that ICAM-1 can be up-regulated by the cytokine IFN-γ on cultured primary human corneal epithelial cells in a dose and time dependent fashion. The expression of corneal epithelial ICAM-1 during inflammation associated with a severe allergic response could contribute to corneal damage by aiding in the attachment of eosinophils.