[en] There exists circumstantial evidence for activation of phospholipase D (PLD) in intact cells. However, because of the complexity of phospholipid remodeling processes, it is essential to distinguish PLD clearly from other phospholipases and phospholipid remodeling enzymes. Therefore, to establish unequivocally PLD activity in dimethyl sulfoxide-differentiated HL-60 granulocytes, to demonstrate the relative contribution of PLD to phospholipid turnover, and to validate the hypothesis that the formation of phosphatidylethanol is an expression of PLD-catalyzed transphosphatidylation, we have developed methodologies to label HL-60 granulocytes in 1-O-alkyl-2-acyl-sn-glycero-3-phosphocholine (alkyl-PC) with 32P without labeling cellular ATP. These methodologies involve (a) synthesis of alkyl-lysoPC containing 32P by a combination of enzymatic and chemical procedures and (b) incubation of HL-60 granulocytes with this alkyl-[32P] lysoPC which enters the cell and becomes acylated into membrane-associated alkyl-[32P]PC. Upon stimulation of these 32P-labeled cells with the chemotactic peptide, N-formyl-Met-Leu-Phe (fMLP), alkyl-[32P]phosphatidic acid (alkyl-[32P]PA) is formed rapidly. Because, under these conditions, cellular ATP has not been labeled with 32P, alkyl-[32P]PA must be formed via PLD-catalyzed hydrolysis of alkyl-[32P]PC at the terminal phosphodiester bond. This result conclusively demonstrates fMLP-induced activation of PLD in HL-60 granulocytes. These 32P-labeled HL-60 granulocytes have also been stimulated in the presence of ethanol to produce alkyl-[32P]phosphatidylethanol (alkyl-[32P]PEt). Formation of alkyl-[32P]PEt parallels that of alkyl-[32P]PA with respect to time course, fMLP concentration, inhibition by a specific fMLP antagonist (t-butoxycarbonyl-Met-Leu-Phe), and Ca2+ concentration