Paf-acether generates chemiluminescence in human neutrophils in the absence of cytochalasin B.

In the absence of cytochalasin B, synthetic Paf-acether (0.1-10 microM) induced oxygen radical production in polymorphonuclear neutrophils as measured by the luminol-dependent chemiluminescence ( LDCL ) test. This effect was observed after a lag period of 10 s and was maximal between 5 and 15 min. In the presence of cytochalasin B, the kinetics were shortened, but the lag period was not modified and the same concentrations of the agonist had to be used to induce LDCL . None of the structural analogs tested (2-lyso Paf-acether, Paf-acether enantiomer, 1 ester analog of Paf-acether, lyso-phosphatidylcholine) were active, irrespective of the presence of cytochalasin B. Paf-acether (10 microM) shortened the kinetics of opsonized zymosan (10 micrograms/ml)-induced LDCL and enhanced it by 550% and 250% at 5 min and 10 min respectively, without affecting the peak value. Similar results were obtained using non-opsonized zymosan (100 micrograms/ml). Lower concentrations of Paf-acether (0.1 microM) were also able to increase oxygen radical production induced by low doses of zymosan and opsonized zymosan. The triggering and enhancing effects of Paf-acether on oxygen radical production by resting and stimulated polymorphonuclear neutrophils support the role of Paf-acether in inflammation.