CD18 integrin and CD54-dependent neutrophil adhesion to cytokine-stimulated human hepatocytes

We investigated the hypothesis that CD54 (intercellular adhesion molecule-1) expressed on hepatocytes will support beta2-integrin (CD18)-dependent adhesion of neutrophils. An in vitro model using C3A cells (a human hepatoblastoma cell line exhibiting many characteristics of normal hepatocytes) and human neutrophils was utilized. C3A cells were stimulated with interleukin-1beta (IL-1beta), tumor necrosis factor-alpha, or interferon-gamma (IFN-gamma) for 24 h to induce expression of CD54, and adhesion of neutrophils was found to be markedly increased. Detailed studies with IFN-gamma-stimulated (100 U/ml) C3A cells revealed that this adhesion involved CD11a/CD18 [lymphocyte function-associated antigen-1 (LFA-1)] and CD54 and was dependent on low levels of IL-8 produced by the stimulated hepatocytes. Addition of higher concentrations of chemotactic factor (e.g., IL-8) further augmented adhesion and recruited contributions of CD11b/CD18 (Mac-1). In contrast to LFA-1, Mac-1 appeared to recognize a CD54-independent ligand constitutively expressed on the hepatocytes. Such close apposition of neutrophils to hepatocytes may increase the potential for parenchymal cell injury by providing a short distance through which cytotoxic factors such as reactive oxygen or proteolytic enzymes could act.