SHP-1: a regulator of neutrophil apoptosis.

The Src homology domain 2 (SH2)-containing tyrosine phosphatase-1 (SHP-1) has been implicated in the regulation of differentiation, proliferation, and activation of hematopoietic cells. In this review, we discuss the potential role of SHP-1 in modulating apoptosis pathways in neutrophils. Low enzymatic SHP-1 was associated with increased neutrophil survival in vitro and SHP-1-deficient mice were reported to develop severe neutrophilic inflammatory responses. In contrast, high expression of this phosphatase was observed in neutropenic patients. Moreover, when neutrophils were exposed to Fas ligand, TNF-alpha, or TRAIL, the anti-apoptotic effects of granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), or IFN-gamma were blocked, most likely by SHP-1-mediated inactivation of anti-apoptotic signaling molecules. In summary, the current available data point to an important role of SHP-1 in the regulation of neutrophil apoptosis.