DFP-sensitive polypeptides of the guinea pig peritoneal macrophage

Guinea pig peritoneal exudate macrophages were reacted with ³H] diisopropyl fluorophosphate (10^?7 to 10^?4 M) and subjected to sodium dodecyl sulfate-polyacrylamide disc electrophoresis and fluorography. Macrophages reacted with 10^?5 M ³H]diisopropyl fluorophosphate contain eight major ³H-labelled polypeptides which have apparent molecular weights of 83,000, 75,000, 63,000, 48,000, 41,000, 30,000, 26,000, and 25,000. The sensitive polypeptides were not seen when guinea pig polymorphonuclear leukocytes, lymph node lymphocytes, erythrocytes, serum or plasma were reacted with ³H]diisopropyl fluorophosphate, demonstrating that these components are particular to the macrophage. The finding of a large number of diisopropyl fluorophosphate-sensitive proteins associated exclusively with the macrophage supports the concept that serine esterases play a unique role in macrophage physiology.