OCULAR SURFACE UP-REGULATION OF INTERCELLULAR ADHESIVE MOLECULE-1 (ICAM-1) BY LOCAL INTERFERON-GAMMA (IFN-GAMMA) IN THE RAT

Inflammatory mediators such as interferon-gamma (IFN-gamma) an known t o induce the expression of class II HLA (HLA-DR) and intercellular adh esion molecule 1 (ICAM-1) in a variety of cell types including epithel ial cells. The coexpression of ICAM-1 and HLA-DR has been implicated i n the pathogenesis of immune mediated ocular disease. We investigated the expression of ICAM-1 on the ocular surface of the rat eye followin g subconjunctival administration of IFN-gamma. A dose response study w as performed using 100, 1,000 and 10,000 IU IFN-gamma/dose. The presen ce of ICAM-1 was determined using a standard immuno-peroxidase stainin g technique. The cornea, limbus, and conjunctiva were evaluated. The d egree of reaction product in each area was graded by a masked observer . We found constitutive expression of ICAM-1 on the conjunctiva but no t on the cornea. There was a significant relationship between the dose of IFN-gamma and the intensity of ICAM-1 staining on the conjunctiva (p less than or equal to 0.05) and on the limbus (p less than or equal to 0.04). Subconjunctival IFN-gamma had no effect on the expression o f ICAM-1 in the cornea.