Eosinophil polymorphonuclear leukocyte function in immediate hypersensitivity.

An eosinophil chemotactic factor of anaphylaxis (ECF-A), released along with other chemical mediators of immediate hypersensitivity from sensitized mast cells that have been challenged with specific antigen, is capable of selectively attracting eosinophils. The rate and magnitude of tissue eosinophil influx may be enhanced by ascorbate and inhibited by the neutrophil immobilizing factor (NIF). Eosinophils may then exercise a local regulatory function. Phagocytosis or the action of ECF-A at high concentrations causes eosinophils to release arylsulfatase, which inactivates slow reacting substance of anaphylaxis (SRS-A). Additional possible functions of eosinophils may follow from their content of factors that inhibit histamine release or its mediator function, and the high levels of intracellular plasminogen and phospholipase B. Thus, the unique enzymes and factors released from eosinophils may form the basis of their role in immediate and subacute hypersensitivity reactions.