Release of PAF-acether from human blood monocytes

Stimulation of human blood monocytes with ionophore A 23187 induced the release of platelet-activating factor (PAF-acether). Phagocytosis of zymosan, coated or not with complement, bacteria or immune complexes, stimulated the release of PAF-acether whereas that of latex particles was without effect. Such release did not occur at 4 degrees C or in the presence of EDTA. PAF-acether derived from monocytes shared the same characteristics as hog leucocyte PAF-acether or synthetic 1-O-alkyl-2-acetyl-glyceryl-3-phosphorylcholine. In lung physiology, the release of PAF-acether from monocytes and alveolar macrophages could lead, via the platelets, to bronchoconstriction. It could represent a cause for asthma other than the classical IgE-mastocyte interaction.