NOS2 and bacterial infectious disease: During L. monocytogenes infection, Ly6Chi CCR2+ cells emigrate from the bone marrow in a CCR2-dependent manor, and traffic to sites of bacterial infection to differentiate into CD11C+ TNF-α and inducible nitric oxide synthase (iNOS) producing DCs (TipDCs) that enhance bacterial clearance [12], [15], [28].