Eosinophil chemotactic factor (ECF). II. Release from human polymorphonuclear leukocytes during phagocytosis

Area of Science:

• Immunology
• Cell Biology

Background:

• Neutrophils (PMN) play a crucial role in immune responses.
• Eosinophil chemotactic factor (ECF) is involved in inflammatory processes.

Purpose of the Study:

• To investigate whether phagocytosis by neutrophils stimulates the release of ECF.
• To characterize the properties of phagocytosis-derived ECF and compare it to other known ECFs.

Main Methods:

• Human neutrophils were exposed to zymosan particles, with or without complement.
• ECF release was measured over time and at different doses.
• Chromatography (Sephadex G-25) was used to analyze ECF.
• Eosinophil attraction and deactivation assays were performed.

Main Results:

• Phagocytosis of zymosan stimulated time- and dose-dependent ECF release from neutrophils.
• Phagocytosis-derived ECF preferentially attracted and deactivated eosinophils.
• ECF release was accelerated by the addition of complement.
• The elution pattern of phagocytosis-derived ECF resembled other known ECFs.
• ECF activity decreased in later time periods, suggesting inactivation.

Conclusions:

• Phagocytosis is a potent stimulus for ECF release from neutrophils.
• Phagocytosis-derived ECF shares functional and chromatographic properties with IgE-induced ECF-A.
• Complement enhances ECF release during phagocytosis.