PROBLEMS ASSOCIATED WITH THE DEMONSTRATION BY LEAD METHODS OF ADENOSINE TRIPHOSPHATASE ACTIVITY IN RESIDENT PERITONEAL MACROPHAGES AND EXUDATE MONOCYTES OF THE GUINEA PIG

This cytochemical and electron microscopic study on peritoneal macrophages of the guinea pig has raised doubts concerning the validity of lead methods for the demonstration of plasma membrane-bound adenosine triphosphatase activity. The problems encountered are inherent in the use of lead ions as a capture reagent. The nonenzymatically formed precipitates reflect sites of heterogeneous nucleation specific for certain kinds of cells, e.g., resident peritoneal macrophages, eosinophilic granulocytes and, to a lesser degree, exudate monocytes. This type of precipitation is also catalyzed on the surface of nonbiologic matrices such as latex particles. Enzymatic processes may well occur, but they cannot be distinguished from nonenzymatic processes.