We have previously reported on suppression of the PGE 2 production in PMA- and calcium ionophore A23187-stimulated macrophages isolated from vitamin E-treated rats. To further study the mechanism, we examined the effect of vitamin E on phospholipase A 2 activity in both intact macrophages and cell-free homogenates measuring the release of [ 14C]arachidonic acid. In macrophages from vitamin E-treated rats, arachidonic acid release in intact cells as stimulated with PMA and calcium ionophore A23187 was hardly detected. In the cell-free homogenates, increase in phospholipase A 2 activity of cytosol and particulate fractions by PMA and A23187 was partially suppressed. In unstimulated macrophages, most of phospholipase A 2 was recovered in the cytosol fraction. The partially purified cytosolic phospholipase A2 showed a molecular mass 95 kDa on TSK gel G3000SW gel-filtration and on Western blot analysis using anti-rabbit platelet phospholipase A 2 monoclonal antibody RHY-5. The activity of cytosolic 95 kDa phospholipase A 2 was not inhibited in vitro by vitamin E. From these results, it was suggested that vitamin E needs intact macrophages to suppress arachidonic acid release.