ACTIVATION OF HUMAN NEUTROPHILS BY ARG-GLY-ASP-SER IMMOBILIZED ON MICROSPHERES

The adhesive interaction of cells with extracellular matrix components is essential for a variety of cellular functions, and is frequently m ediated by a tetra peptide, Arg-Gly-Asp-Ser (RGDS), located within fib ronectin and other proteins. In this study, the RGDS-mediated activati on of polymorphonuclear leukocytes accompanied by phagocytosis was inv estigated using monodisperse polymeric microspheres carrying RGDS. The parent and Arg-Gly-Glu-Ser (RGES)-carrying microspheres, which have n o adhesion activity, were employed as controls. The ingestion of micro spheres into PMN was not enhanced by immobilizing RGDS. However, PMNs exhibited unique oxygen consumption and enhanced Liberation of reactiv e oxygen when RGDS-carrying microspheres were phagocytosed. These PMN responses disappeared with the addition of soluble RGDS. Furthermore, cytochalasin D, which inhibits actin polymerization, showed a marked i nhibitory effect on oxygen consumption in the RGDS-carrying microspher e system, as compared with those in other systems. These findings show that RGDS-carrying microspheres induced the biospecific activation of PMNs by the signal transduction via RGDS-integrin binding without alt eration in the degree of phagocytosis. (C) 1994 John Wiley and Sons, I nc.