c-Abl Kinase Is Required for β2 Integrin-Mediated Neutrophil Adhesion

Integrin regulation in neutrophil adhesion is essential for innate immune response. c-Abl kinase is a nonreceptor tyrosine kinase and is critical for signaling transduction from various receptors in leukocytes. Using neutrophils and dHL-60 (neutrophil-like differentiation of HL-60) cells, we show that c-Abl kinase is activated by β2 integrin engagement and is required for β2 integrin-dependent neutrophil sustained adhesion and spreading. The expression of β2 integrin on neutrophils induced by TNF-α is not affected by c-Abl kinase inhibitor STI571, suggesting that c-Abl kinase is not involved in TNF-α-induced integrin activation. The recruitment of c-Abl kinase to β2 integrin is dependent on talin head domain, which constitutively interacts with β2 integrin cytoplasmic domain. After activated, c-Abl kinase increases the tyrosine phosphorylation of Vav. The SH3 domain of c-Abl kinase is involved in its interaction with talin and Vav. Thus, c-Abl kinase plays an essential role in the activation of Vav induced by β2 integrin ligation and in regulating neutrophil-sustained adhesion and spreading.