Recruitment of CD11b/CD18 to the neutrophil surface and adherence-dependent cell locomotion.
Chemotactic stimulation of neutrophils results in translocation of CD11b/CD18 (Mac-1) from intracellular storage pools to the cell surface. Though results from several laboratories indicate that the newly arrived surface Mac-1 is not involved in the adherence induced by the initial stimulus, the present study addresses the hypothesis that this Mac-1 plays a role in subsequent adherence-dependent functions. The response of human neutrophils to changing concentrations of a chemotactic stimulus was evaluated by determining the amount of newly arrived surface Mac-1, and Mac-1-dependent adhesion and locomotion. Small step-wise increases in the concentration of f-Met-Leu-Phe (FMLP) resulted in proportional stepwise increases in surface Mac-1 that plateaued within 2-4 min. This newly arrived Mac-1 supported adhesion to protein-coated surfaces only when the cells were exposed to an additional increase in the FMLP stimulus level. Adherence-dependent cellular locomotion was evaluated in chambers that allowed rapid changes in the stimulus concentration. Repeated small increments in the stimulus level at 200-s intervals resulted in significantly longer migration paths than a single-step increase in the stimulus. The results support the hypothesis that small increments in the chemotactic stimulus bring Mac-1 to the cell surface, and this newly mobilized Mac-1 is available for adherence-dependent locomotion with subsequent increases in the concentration of the stimulus.
Speros Martel Section of Leukocyte Biology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030-2399.
B J
BJ
Hughes
J C
JC
Hollers
E
E
Crockett-Torabi
C W
CW
Smith
D000328:Adult; D015703:Antigens, CD / Q000032:analysis / Q000502:physiology*; D018845:CD11 Antigens; D018821:CD18 Antigens; D002118:Calcium / Q000502:physiology; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000502:physiology; D002465:Cell Movement; D004305:Dose-Response Relationship, Drug; D006801:Humans; D066298:In Vitro Techniques; D018799:Intercellular Adhesion Molecule-1; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000502:physiology*
D015703:Antigens, CD; D018845:CD11 Antigens; D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; D018799:Intercellular Adhesion Molecule-1; D009240:N-Formylmethionine Leucyl-Phenylalanine; D002118:Calcium