Histamine secretion from human leucocytes stimulated by basophil-derived platelet-activating factor.

Crude preparations of platelet-activating factors (PAF) derived by methanolic extraction of supernatants from antigen-challenged basophils generally stimulated the secretion of histamine from human peripheral blood leucocytes when co-incubated with these cells in the absence of an additional stimulator. When these crude preparations were analysed by a preparative thin-layer chromatography technique established for the isolation of purified native PAF, multiple lipid components were identified. The component that migrated in accordance with native PAF, and which activated platelets to aggregation/secretion, was responsible for the induction of histamine release previously seen with the crude PAF preparations and could augment histamine secretion from leucocytes undergoing stimulation with either the biologically active peptide F-Met-Leu-Phe or with antigen E. These data suggest that basophil-derived PAF may serve as an important endogenous feedback mechanism during basophil activation in addition to its modulatory role upon the platelet.