CD177 ligation activates neutrophils in a β2 integrin-dependent manner. (A) Neutrophils were incubated with αCD177 or isotype (10 µg/mL × 30 min), with or without LTB₄ 100 nM, followed by assessment of surface activation by flow cytometry. (B) Quantitation of change in surface activation markers in CD177^pos versus CD177^neg cells. Panels A and B reflect pooled data from 3 individual donors. (C) Activation of neutrophils from a CD177^null donor was not affected by αCD177. Data are pooled from 2 replicate experiments. (D) Peripheral blood neutrophils were incubated with αCD177 or isotype 10 µg/mL ± LTB₄ 100 nM at 37°C for times as are indicated, detecting Src and ERK activation by western blot. (E) Phosphorylation of Src and ERK by αCD177 is inhibited by contemporaneous addition of blocking antibody against CD18 (MEM148, 10 µg/mL). Panels D and E are representative of 3 experiments in neutrophils from 2 donors. Means ± SEMs. **P < .01; ***P < .001; ****P < .0001; by 2-way ANOVA (A-B). Max, maximum; Min, minimum.