Motility and adhesiveness in human neutrophils. Redistribution of chemotactic factor-induced adhesion sites

Abstract

Human peripheral blood neutrophils obtained from healthy adults were examined in vitro. We assessed the effects of sequential stepwise increases in the concentration of the chemotactic dipeptide N-formyl-l-methionyl-l-phenylalanine (f-Met-Phe) on neutrophil attachment to serum-coated glass, detachment from serum-coated glass and the distribution on the cell surface of binding sites for albumin-coated latex beads. The initial exposure to f-Met-Phe resulted in increased adhesiveness and binding of latex beads in a random pattern over the cell surface. The second exposure to f-Met-Phe resulted in decreased adherence, detachment of neutrophils from serum-coated glass, and movement of binding sites for latex beads to the uropod. Enhanced adhesiveness and redistribution of binding sites were blocked by 0.1 mM N-alpha-p-tosyl-l-lysine chloromethyl ketone, a concentration that did not reduce the change in cellular shape caused by f-Met-Phe. Cytochalasin B (5 mug/ml) blocked the redistribution of binding sites as well as the change in shape. The third exposure to f-Met-Phe was given along with the latex beads. The stimulus was stopped after 2 min by fixing cells in suspension with glutaraldehyde. If the third exposure was at a concentration higher than the second, the beads were bound in the region of the lamellipodia in 70% of the cells. If lower, binding to the lamellipodia was found in a significantly smaller proportion of cells (13%). The results support the concept that neutrophils develop a polarized distribution of f-Met-Phe-induced adhesion sites in response to increasing concentrations of f-Met-Phe, and these sites flow from the region of the lamellipodia to the uropod.