Chemotactic deactivation of human eosinophils by the eosinophil chemotactic factor of anaphylaxis (38527).

Purified human eosinophils demonstrate diminished chemotactic responsiveness (deactivation) after incubation with the eosinophil chemotactic factor of anaphylaxis (ECF-A). The deactivation is rapid and selective in that ECF-A deactivated human eosinophils more markedly than neutrophilic or mononuclear leukocytes. The eosinophil can also be deactivated by C5a which is eosinophilotactic, and there is cross deactivation between C5a and ECF-A. Deactivation may be an important physiologic control mechanism enabling the eosinophil to remain at sites of ECF-A release in order to manifest its regulatory functions in immediate hypersensitivity reactions.