CD177 is a GPI-anchored protein expressed by a variable proportion of human neutrophils that mediates surface expression of the anti-neutrophil cytoplasmic antibody (ANCA) antigen proteinase 3. CD177 associates with β2 integrins and recognizes PECAM-1, suggesting a role in neutrophil migration. However, CD177pos neutrophils exhibit no clear migratory advantage in vivo, despite interruption of transendothelial migration by in vitro CD177 ligation. We sought to understand this paradox. Using a PECAM-1-independent transwell system, we found that CD177pos and CD177neg neutrophils migrated comparably. CD177 ligation selectively impaired migration of CD177pos neutrophils, an effect mediated through immobilization and cellular spreading on the transwell membrane. Correspondingly, CD177 ligation enhanced its interaction with β2 integrins as revealed by fluorescence lifetime imaging microscopy, leading to integrin-mediated phosphorylation of Src and ERK. CD177-driven cell activation enhanced surface β2 integrin expression and affinity, impaired internalization of integrin attachments, and resulted in ERK-mediated attenuation of chemokine signaling. We conclude that CD177 signals in a β2 integrin-dependent manner to orchestrate a set of activation-mediated mechanisms that impair human neutrophil migration. [ABSTRACT FROM AUTHOR]