Biochemical Demonstration of the Activatable Esterase of the Rabbit Neutrophil Involved in the Chemotactic Response

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Abstract
Direct biochemical evidence is provided that the rabbit blood neutrophil contains a precursor esterase involved in the cell response to the chemotactic stimulus C567, and that contact of the cell with chemotactic factor leads to activation of the proesterase. Rabbit blood leukocytes contain esterase 1, that is, an enzyme capable of hydrolyzing acetyl-dl-phenylalanine β-naphthyl ester. This activity can be ascribed largely, if not entirely, to the presence of neutrophils. Comparing blood leukocytes with peritoneal (exudate) neutrophils, the former cells contain greater esterase activity as well as greater chemotactic responsiveness. Treatment of blood leukocytes, but not peritoneal neutrophils, with chemotactic factor results in the acquisition of esterase activity (“esterase activation”) and chemotactic deactivation (loss of chemotactic responsiveness). By using highly purified complement and preparative (density gradient) ultracentrifugation, and employing agents that dissociate the macromolecular chemotactic factor, the phenomena of chemotactic activity, esterase-activating capacity and deactivating potential have been shown to be interrelated and clearly ascribable to C567. The esterase that appears in the blood leukocyte as a result of interaction with C567 can be identified as esterase 1, on the basis of exquisite sensitivity to inhibitory effects of phosphonate compounds at very low concentrations (10-8 M). These data provide direct biochemical support for the original hypothesis that the chemotactic response of the neutrophil to the complement chemotactic factor C567 involves an interaction which results in the conversion of the cell-bound proesterase to an active esterase. The biochemical role of this esterase in the kinetic behavior of the granulocyte is not known. This information may have special relevance to at least four other phenomena in which activation of a protesterase to an active esterase as the cause of an “allergic response” has been postulated on the basis of indirect evidence.

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