STIMULATION OF P-SELECTIN GLYCOPROTEIN LIGAND-1 ON MOUSE NEUTROPHILS ACTIVATES BETA(2)-INTEGRIN MEDIATED CELL ATTACHMENT TO ICAM-1

The entry of neutrophils into inflamed tissues is initiated by cell ro lling on the blood vessel wall followed by arrest and transendothelial migration. Rolling is mediated by the selectins, while the two subseq uent steps require activated beta(2)-integrins. We have investigated w hether the binding of P-selectin to mouse neutrophils could trigger th e activation of beta(2)-integrins. We show that cross-linking of P-sel ectin glycoprotein ligand-l (PSGL-1) on mouse neutrophils with an anti body-like recombinant form of P-selectin or with monoclonal antibodies stimulated the production of reactive oxygen intermediates and enhanc ed neutrophil attachment to intercellular adhesion molecule 1 (ICAM-1) -expressing CHO cells. This effect was independent of whether complete antibodies or F(ab')(2) fragments were used. The adhesion-stimulating effect of P-selectin could be blocked by monoclonal antibodies agains t PSGL-1. Increase of cell attachment was dependent on lymphocyte func tion-associated antigen 1 (LFA-1) and on Mac-1, since it could be bloc ked with antibodies against both respective integrin alpha-chains. Mor eover, cell surface expression of Mac-1 increased upon cross-linking o f PSGL-1. In agreement with published data, treatment of human neutrop hils with P-selectin-IgG did not enhance attachment to ICAM-1. Our dat a suggest that ligation of PSGL-1 on mouse neutrophils, but not on hum an neutrophils, activates beta(2)-integrin mediated cell attachment to ICAM-1.