Contributions of LFA-1 and Mac-1 to time-dependent changes in cell adhesivity. Neutrophils (3 × 106cells/mL) were mixed with E3-ICAM transfectants (6 × 106 cells/mL) and stimulated with 1 μmol/L FMLP for fixed time periods (0, 30, 60, 120, 180, 240, or 300 seconds) before application of shear at 200 s−1. Cell aggregation kinetics was measured. (A) Percent neutrophils in heterotypic aggregates for experiments where shear was applied either 0, 30, 120, or 300 seconds after stimulation. (B) Percent neutrophils recruited in heterotypic aggregation when shear was applied 120 seconds after FMLP stimulation either in the absence of MoAb (LFA-1– and Mac-1–dependent adhesion) or on addition of anti–ICAM-1 domain 1 MoAb RR1/1 (Mac-1–dependent adhesion) or anti–Mac-1 MoAb h60.1 (LFA-1–dependent adhesion). Error bars in (A) and (B) represent SEM from three independent experiments. (C) Adhesion efficiency of neutrophil–E3-ICAM interactions with time at a shear rate of 200 s−1 either in the absence of MoAb, or upon addition of MoAbs to domain-1 of ICAM-1 (RR1/1) or Mac-1 (h60.1). Smooth lines represent curve fit to experimental data with a first-order exponential decay function as described in Results. Data are means from at least three independent experiments. *P < .05 with respect to adhesion efficiency estimated in the absence of MoAb and on addition of RR1/1.
