S100A12 and S100A9 are calcium-binding proteins highly expressed in neutrophils and reflect their inflammatory state. CSF3R (CD114, G-CSF receptor) is a surface receptor involved in neutrophil development and survival. CXCR2 is a chemokine receptor mediating neutrophil recruitment to sites of inflammation, and FCGR3B (CD16b) is a neutrophil-specific isoform of CD16 distinguishing neutrophils from NK cells and monocytes that express FCGR3A. Together these markers reliably identify neutrophils and distinguish them from other myeloid cell populations.
