Shear-induced adhesion of unstimulated neutrophils to ICAM-1 transfectants.

Neutrophils (1 × 10⁶ cells/mL) were preincubated for 10 minutes with saturating concentrations of monoclonal antibodies to CD11a or CD11b. They were then mixed with I_high(2 × 10⁶ cells/mL), added to the cone-plate viscometer, and allowed to equilibrate for 2 minutes before initiation of fluid shear. Samples were taken at prescribed time points, fixed, and detected by flow cytometry as described in “Materials and Methods.” (A) Kinetics of aggregation are plotted for I_high at a shear rate of 466 s⁻¹. (B) Peak extent of shear-induced aggregation occurred within 1 minute of initiation of shear and is plotted for I_high over a range of shear rates and antibody blocking conditions. *P < .01 compared with control at the same shear rate; **P < .05 compared with control and with concurrent block of CD11a and CD11b at the same shear rate. (C) Data from Figure 4B were modeled to calculate adhesion efficiency over the first 60 seconds after initiation of shear, as described in “Materials and Methods.” Smooth lines represent curves fit to experimental data with a first-order exponential decay function. *P < .05 compared with control at the same shear rate. Data are presented as mean ± SEM from 3 to 6 separate experiments.