Leukotriene B4 stimulation of phosphatidylinositol turnover in macrophages and inhibition by pertussis toxin.

The influence of leukotriene B4 (LTB4) on phosphatidylinositol (PI) cycle activity was investigated in the guinea pig alveolar macrophage. In contrast to the observation reported in leukocytes [(1984) Proc. Natl. Acad. Sci. USA 81, 5966-5969], LTB4 was found to stimulate PI cycle activity in the macrophage (transient decrease in phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 4-phosphate, transient elevation of 1,2-diacylglycerol and elevation of phosphatidic acid) similar to the stimulation of the PI cycle by the chemotactic formyl peptides. Preincubation of macrophages with 1 microgram/ml of pertussis toxin, for 1 h at 37 degrees C, blocked LTB4 and formyl peptide stimulated O-2 production and PI cycle activity. Therefore, both stimulants are proposed to act through the same coupling protein to activate phospholipase C in the early stages of macrophage activation.