While nonclassical monocytes (CD14+CD16++) are long-lived and ‘patrol’ healthy tissues through long-range crawling on the endothelium, classical (CD14++CD16-) and intermediate (CD14++CD16+) monocytes are recruited to the lung in response to viral infection, where they secrete inflammatory cytokines and chemokines, as well as type I interferons (IFNs) (7, 9–11). Here, CD14 is linked to viral infectious disease.