Modulation by cytokines on the surface expression and shedding of intercellular adhesion molecule-1 (ICAM-1) in human liver cancer cell lines

Abstract Surface expression and shedding of intercellular adhesion molecule-1 (ICAM-1) in the absence and presence of cytokines were measured in seven human liver cancer cell lines. All cancer cell lines were positive for ICAM-1 on the surface of the cells, and the percentages of positive cells ranged from 60 to 97% as analyzed by flow cytometry. Mean fluorescence was increased in the presence of IL-1β, TNF-α, IFN-α or IFN-γ, and the effect was augmented in a dose-dependent fashion. In the culture medium of all cancer cell lines, a soluble form of ICAM-1 was detected even in the absence of cytokines by enzyme-linked immunosorbent assay, and the concentration was increased by IL-1β, TNF-α, or IFN-γ. In two of seven cancer cell lines, the patterns of modulation by cytokines on the surface expression of ICAM-1 and the shedding of the molecules were clearly distinct, suggesting that the mechanisms for these two phenomena might be different. Soluble ICAM-1 was recently reported to suppress non-MHC-restricted cytotoxicity mediated by natural killer and lymphokine-activated killer cells. Our present data suggest that human liver cancer cells may escape from host immune surveillance by shedding of ICAM-1.