%0 Journal Article %J J. Clin. Invest. %D 1997 %T Neutrophil accumulation on activated, surface-adherent platelets in flow is mediated by interaction of Mac-1 with fibrinogen bound to αIIbβ3 and stimulated by platelet-activating factor %A Weber,C. %A Springer, T.A. %X

We have studied the pathways that lead to arrest and firm adhesion of rolling PMN on activated, surface-adherent platelets. Stable arrest and adhesion strengthening of PMN on thrombin-stimulated, surface-adherent platelets in flow required distinct Ca2+- and Mg2+-dependent regions of Mac-1 (alphaMbeta2), and involved interactions of Mac-1 with fibrinogen, which was bound to platelets via alphaIIbbeta3. Mac-1 also bound to other unidentified ligands on platelets, which were not intracellular adhesion molecule-2 (ICAM-2), heparin, or heparan-sulfate proteoglycans. This was shown by inhibition with mAbs or peptides, by treatment of platelets with heparitinase, and by using platelets with defective alphaIIbbeta3 from a patient with Glanzmann thrombasthenia. Tethering of PMN on platelet ICAM-2 via LFA-1 (alphaLbeta2) was observed, which may facilitate the transition between rolling on selectins and Mac-1-dependent arrest. Arrest and adhesion strengthening was pertussis toxin sensitive and in flow was mainly induced by platelet-activating factor but not through activation of the chemokine receptor CXCR2. In stasis, spreading occurred and the CXCR2 contributed to firm adhesion.

%B J. Clin. Invest. %V 100 %P 2085-2093 %G eng %N 8 %1 374 %! J. Clin. Invest. %F 374