Platelet-activating factor. A potent chemotactic and chemokinetic factor for human eosinophils.

TLDR

Platelet‑activating factor (PAF‑acether) is an inflammatory mediator known to induce neutrophil aggregation and chemotaxis, and its effect on human eosinophil locomotion was investigated. The study used human eosinophils of 25–95 % purity isolated from donors with various hypereosinophilic diseases. PAF‑acether induced dose‑ and time‑dependent chemotaxis and chemokinesis of eosinophils (10⁻⁵–10⁻⁸ M), whereas lyso‑PAF and other chemoattractants such as LTB4, histamine, and ECF‑A had minimal effect, neutrophils responded similarly to PAF‑acether and LTB4, and light‑density eosinophils showed slightly greater locomotion, indicating that PAF‑acether is a potent eosinophilotactic agent that may contribute to eosinophil‑mediated inflammation.

Abstract

Platelet-activating factor (PAF-acether), an inflammatory mediator with a wide range of biological activities including neutrophil aggregation and chemotaxis, was studied for its effect on human eosinophil locomotion (chemotaxis and chemokinesis). Human eosinophils (25-95% purity) were obtained from donors with a variety of diseases associated with hypereosinophilia. PAF-acether elicited directional locomotion of eosinophils, in a time- and dose-dependent fashion, at concentrations from 10(-5) to 10(-8) M; lyso-PAF had minimal activity over the same dose range. Compared with PAF-acether, the eosinophil locomotory responsiveness of leukotriene B4 (LTB4), histamine, and the valyl- and alanyl-eosinophil chemotactic factor of anaphylaxis (ECF-A) tetrapeptides was negligible. Conversely, neutrophil responsiveness to PAF-acether (optimum 10(-6) M) was comparable in effect to LTB4 (optimum dose 10(-8) M). It was shown that PAF-acether elicited both chemotaxis and chemokinesis of eosinophils. Comparison of normal density and light density eosinophils revealed no qualitative difference in the response to PAF-acether and the other chemoattractants, although the light density cells seemed to demonstrate a greater degree of locomotion to PAF-acether and LTB4. Thus, PAF-acether appears to be a potent eosinophilotactic agent which may play a role in inflammatory reactions characterized by eosinophil infiltration.