IgG-enhanced leukocyte recruitment requires E-selectin and β₂ integrins. (A) Flow cytometry showing basal expression of E-selectin (mAb 1.2B6, dotted line) and ICAM-1 (mAb 6.5B5, black line) and increased expression following TNFα stimulation (10 ng/mL for 4 hours). The filled histograms show lack of reactivity of control mAb MOPC21. (B-E) Inhibition of RMAC8-mediated PMN (B,D) and HL60 cell (C,E) adhesion at 1.5 dynes/cm² to TNFα-stimulated ECs by (B,C) anti-E-selectin (mAb SPLAT-1), anti-β₂ integrin (mAb TS1/18), anti-αL (mAb TS1/22), or anti-αM (mAb 44), or (D,E) anti-FcγRIIa (IV.3), but not by fab′ anti-FcγRIIIb (3G8). Values are mean ± SEM of 3 experiments (*P < .01, **P < .03).