Lipopolysaccharide in Combination with Serum Potentiates the Stimulated Activity of Phospholipase D in Human Neutrophils Via CD14

The addition of fMet-Leu-Phe or phorbol12- myristate13-acetate to human neutrophils stimulates phospholipase Dactivity as evidenced by the release of phosphatidic acidand the generation of diacylglycerol, and in the presence of ethanol the formation of phosphatidyl ethanol. The activation of phospholipase Dby either the chemotactic factor or active phorbol esteris inhibited by the tyrosine kinase inhibitorerbstatin. The fMet-Leu-Phe-induced stimulation of this enzyme is greatly potentiated in cells which have been preincubated with low concentrations of lipopolysaccharideand serum. The presence of serum is essential for the potentiation by low concentrations of lipopolysaccharide. Moreover, the monoclonal antibody MY4(IgG2b) against CD14inhibits the potentiation by the low concentration of lipopolysaccharide. These data suggest three important points. First, a tyrosine kinasestep is necessary for the activation of phospholipase D. This suggests that the phospholipase Denzyme needs to be phosphor...