CONSTITUTIVE NEUTROPHIL APOPTOSIS IN CULTURE IS MODULATED BY CELL-DENSITY INDEPENDENTLY OF BETA(2) INTEGRIN-MEDIATED ADHESION

Although inflammatory mediators modulate the rate of constitutive neut rophil apoptosis in vitro the effects of microenvironmental conditions have not been fully investigated, In this study, we demonstrate that the rate of constitutive neutrophil apoptosis is affected by the numbe r of cells per unit surface area, with enhanced survival at high cell density, Furthermore, the presence of protein or serum in the culture medium also enhances neutrophil survival, These effects were independe nt of beta(2) integrin-mediated adhesion and were not influenced by sp ecific adhesion to extracellular matrix components, Thus, the rate of neutrophil apoptosis is fundamentally influenced by microenvironmental conditions and indicates that factors such as cell density and extrac ellular protein concentration must be considered when investigating me chanisms regulating inflammatory cell apoptosis in vitro, (C) 1998 Fed eration of European Biochemical Societies.