Ca2+ influx initiates death of hepatocytes injured by activation of complement

To clarify the role of cytosolic Ca2+ in hepatocellular death, we exposed cultured hepatocytes to human serum and a monoclonal antibody directed against rat liver plasma membranes to produce complement-mediated cell injury. The change in cytosolic Ca2+ concentration was measured by fura2 and fluo3 fluorescence. With the addition of monoclonal antibody, an increase in cytosolic Ca2+ was observed, followed by cell death. Both the increase in intracellular Ca2+ and cell death were prevented by intracellular Ca2+ chelation or removal of extracellular Ca2+. We conclude that an increase in cytosolic Ca2+ plays a major role in hepatocellular injury induced by exposure of the cell membrane to monoclonal antibody.