THE REQUIREMENT OF SERINE ESTERASE FUNCTION IN COMPLEMENT-DEPENDENT ERYTHROPHAGOCYTOSIS

Abstract

The p-nitrophenyl ethyl phosphonate esters have been shown to inhibit complement-dependent erythrophagocytosis when exposed to guinea pig polymorphonuclear leukocytes prior to the initiation of phagocytosis. Inhibition of phagocytosis occurred in a manner characteristic of the well-defined capacity of phosphonate esters to inactivate serine esterases: inhibition was irreversible, dependent upon the temperature of reaction and pH of the reaction medium, and proportional to the concentration of inhibitor used and the duration of exposure between leukocytes and inhibitor. Phosphonate inhibition was further shown to be independent of any general cell damaging effects of the compounds used. The phagocytic enzyme inhibited by phosphonate esters apparently exists in or on leukocytes in an already activated state prior to the initiation of the phagocytic process.