ICAM-1 expression in a spontaneously transformed human keratinocyte cell line: Characterization by a simple cell-elisa assay

Abstract

Interferon gamma (IFN-γ) is known to induce ICAM-1 on keratinocytes (KC) in vitro, and its expression in vivo is correlated with epidermal T-cell infiltration in various dermatoses. However, the mechanisms for this cytokine-mediated ICAM-1 expression are essentially unknown. We investigated the induction of ICAM-1 by IFN-γ in HaCaT cells, a spontaneously transformed human KC cell line, using an immunoperoxidase-ELISA with the monoclonal antibody (MoAb) R6.5. HaCaT cells constitutively expressed low levels of ICAM-1, which were upregulated by IFN-γ. The kinetics and dose response were similar to those published for primary KC, regardless of whether the HaCaT cells were cultured in lowor high-calcium medium. ICAM-1 expression was increased significantly at 4 h with 500 U/ml IFN-γ, and reached a plateau (∼ 5 × > constitutive) by 24 h. At concentrations greater than 10 U/ml for 24 h, IFN-γ induced ICAM-1 expression in a dose-dependent fashion (half maximal at 100 U/ml). TNF-α alone, and in synergistic combination with IFN-γ, also upregulated the expression of HaCaT ICAM-1. IFN-γ treatment of HaCaT cells increased the level of ICAM-1 mRNA and enhanced (∼ 3×) the adherence of fluorescently labeled (calcein) human T lymphoblasts, as determined by Northern blotting and an in vitro adhesion assay, respectively. Our findings suggest that HaCaT cells, in conjunction with a simple immunoperoxidase cell-ELISA, provide a reliable system for studying pharmacologic modulation of ICAM-1 on KC. © 1992.