Ly6G+ Neutrophils Are Dispensable for Defense against Systemic Listeria monocytogenes Infection

Listeria monocytogenes is a facultative intracellular bacterium that causes systemic infections in immunocompromised hosts. Early recruitment of myeloid cells, including inflammatory monocytes and neutrophils, to sites of L. monocytogenes infection is essential for the control of infection and host survival. Because previous experimental studies used depleting or blocking Abs that affected both inflammatory monocytes and neutrophils, the relative contributions of these cell populations to defense against L. monocytogenes infection remain incompletely defined. In this article, we used highly selective depletion strategies to either deplete inflammatory monocytes or neutrophils from L. monocytogenes-infected mice and demonstrate that neutrophils are dispensable for early and late control of infection. In contrast, inflammatory monocytes are essential for bacterial clearance during the innate and adaptive phases of the immune response to L. monocytogenes infection.