To answer this question, we depleted granulocytes 24 hours prior infection after carefully titrating the antibody. Depletion of neutrophils was close to complete (Fig. 7A) , while changes in other cell populations were negligible ( Figure S3 ). Ex vivo analysis of luciferase activity in IFN-b +/Db-luc mice depleted of neutrophils revealed, that these cells did not have a significant impact on luciferase expression (Fig. 7B ). In addition, similar amounts of IFN-b and total IFN-a in serum were found in C57BL/6 mice despite of the neutrophil depletion (Fig. 7C) . Hence, LysM-positive monocyte/macrophages are the population that is responsible to almost entirely produce type I IFN after Listeria monocytogenes infection.