Inhibition of activation of human peripheral blood eosinophils by Y-24180,an antagonist to platelet-activating factor receptor

We examined the effects of Y-24180, a potent and long-acting antagonist to platelet-activating, factor (PAF) receptor, on the PAF- or leukotriene B-4 (LTB4)-induced activation of eosinophils using human peripheral blood in vi tro. As activation markers, CD11b expression level and soluble intercellula r adhesion molecule-1 (sICAM-1)-binding activity were analyzed by now cytom etry. Y-24180 significantly inhibited PAF-induced increase in the ratio of strongly positive cells for CD11b expression and sICAM-1 binding at 0.01 mu M or more. WEB 2086, another PAF receptor antagonist, also inhibited the i ncrease significantly at 1 mu M or more. LTB4-induced increases in the rati o of strongly positive cells for CD11b expression and sICAM-1 binding were inhibited by Y-24180 at 1 mu M, but not WEB 2086 up to 10 mu M. These resul ts indicate that Y-24180 inhibits the PAF- or LTB,-induced activation of eo sinophils in human peripheral blood more potently than WEB 2086. (C) 1999 E lsevier Science Inc.