Effect of mechanical deformation of neutrophils on their CD18/ICAM-1-dependent adhesion

Mechanical deformation of polymorphonuclear leukocytes (PMN) changes their expression of the surface adhesion molecule CD11b/CD18. We tested the hypothesis that mechanical deformation of PMN enhances their adhesiveness. Purified human PMN were deformed through either 5- or 3-μm polycarbonate membrane filters and allowed to adhere to 96-well plates coated with human recombinant intercellular adhesion molecule-1 (ICAM-1). Flow cytometric studies showed that deformation of PMN increased CD11b/CD18 expression ( P < 0.01). PMN adhesion to ICAM-1-coated plates was dependent on the magnitude of cell deformation (5 μm, 63.8 ± 8.1%, P < 0.04; 3 μm, 232.4 ± 20.9%, P < 0.01). Priming of PMN (0.5 nM N -formyl-methionyl-leucyl-phenylalanine) before deformation (5 μm) increased PMN adhesion (63.8 ± 8.1 vs. 105.3 ± 16.4%; P < 0.04). Stimulation (5% zymosan-activated plasma) of PMN after deformation resulted in increased adhesion, and the degree of increase was dependent on the magnitude of PMN deformation (stimulation, 50.6 ± 4%; 5-μm filtration and stimulation, 62.9 ± 6.6%; 3-μm filtration and stimulation, 249.9 ± 24.2%; P < 0.01). This study shows that mechanical deformation of PMN causes an increase in PMN adhesiveness to ICAM-1 that was enhanced by both priming of PMN before deformation and stimulation after cell deformation.