Synthesis and release of platelet-activating factor and eicosanoids in human endothelial cells induced by different agonists.

Production of platelet-activating factor (PAF) and eicosanoids by human umbilical vein endothelial cells (HUVEC) after stimulation with different agonists has been studied. Significant amounts of PAF were measured in the cellular fraction after treatment with thrombin (2 NIHu/ml), calcium ionophore A23187 (2 μM) and histamine (100 μM) (110.3±14.3, 80.7±19.2 and 119.2±22.4 pg/105 cells, respectively). Only thrombin caused a partial release of PAF into the supernatant. IL-1α (0.1 nM), TNF (1 nM), arachidonic acid (10 μM) and endothelin (0.1 μM) were not able to induce any PAF synthesis. High levels of 6-keto-PGF1α were found after stimulation with thrombin and calcium ionophore A23187 (8641±2575 and 6715±3340 pg/105 cells, respectively). Cytokines IL-1α and TNF were also able to stimulate PGI2 synthesis, although to a lesser extent. PGE2 production increased after treatment with thrombin and calcium ionophore A23187 three- and two-fold, respectively. Our results confirm that stimulated HUVEC are able to synthesize PAF and eicosanoids simultaneously, the relative amounts depending upon the agonist used. None of the agonists studied showed any significant effect on 15-HETE production.