We examined the changes of phospholipase A2 (PLA2) activity and of reduced glutathione (GSH), Ca2+, and lipid peroxide (LPO) contents in isolated rat hepatocytes treated with anti-liver cell plasma membrane antiserum (ALPMA) following the development of immunological cell injury. Increases in PLA2 activity and Ca2+ content and a decrease in GSH content in the ALMA-treated hepatocytes occurred with an increase in release of alanine and asparatate transaminases from the cells. After these changes occurred, LPO level increased in the ALPMA-treated hepatocytes. These results suggest that in ALPMA-treated rat hepatocytes, depletion of intracellular GSH, which has a function of cell membrane stabilization, followed by increases in Ca2+ level and PLA2 activity primarily contributes to immunological cell injury and that stimulation of intracellular LPO production consequent of increased PLA2 activity is secondarily contributory to the cell injury.