EFFECTS OF PROINFLAMMATORY CYTOKINES ON CULTIVATED PRIMARY HUMAN HEPATOCYTES - FLUOROMETRIC MEASUREMENT OF INTERCELLULAR-ADHESION MOLECULE-1 AND HUMAN-LEUKOCYTE ANTIGEN-A, ANTIGEN-B, ANTIGEN-C, AND ANTIGEN-DR EXPRESSION

Expression of adhesion molecules and human leukocyte antigens on the s urface of hepatocytes (HC) may play an important role in the immune re action in different types of infectious and noninfectious hepatitis, l iver graft rejection, and autoimmune liver diseases. The aim of this s tudy was to evaluate the influence of the proinflammatory cytokines IF N-alpha, IFN-gamma, and IL-1 alpha on the expression of intercellular adhesion molecule-1 (ICAM-1) and HLA-A, -B, -C, and -DR on highly puri fied primary human HC in cell culture, Expression was assessed by semi quantitative measurement of HC in cell culture by means of computer-ai ded fluorometry after immunofluorescent labeling. Avidin-biotin-immuno peroxidase staining was applied on parallel cultures to evaluate cell purity (>99%) and to confirm the results obtained by fluorometry. ICAM -1 was expressed constitutively on untreated HC in vitro. Stimulation of HC with IFN-gamma and IL-1 alpha for 24 hr resulted in an increase of ICAM-1 expression. Cultured HC were moderately HLA-A, -B, and -C po sitive, but HLA-DR negative. Stimulation of HC with 500 U/ml IFN-gamma for 72 hr resulted in an increase of HLA-A, -B, -C, and -DR expressio n, whereas stimulation with 10 U/ml IL-1 alpha for 72 hr had no influe nce. By using 5000 U/ml IFN-alpha for 72 hr, we achieved an increase o f HLA-A, -B, and -C expression; effects on the other tested antigens w ere not significant. In contrast to endothelial cells and transformed human hepatocytic cell lines, ICAM-1 on HC was changed more intensivel y by IFN-gamma than by IL-1 alpha. Furthermore, the results reveal dif ferences in HLA and ICAM-1 expression between HC in vivo and in vitro.