Infection with Aspergillus fumigatus can lead to aspergillosis in immunocompromised people as well as allergic asthma in atopic patients. In PLoS Pathogens, Levitz and colleagues investigate the role of eosinophils in models of A. fumigatus infection and allergy. Pulmonary eosinophils interact with A. fumigatus conidia, which results in the killing of these fungi. The activity of eosinophils is critical, as their absence results in much greater mortality after infection with a virulent strain of A. fumigatus. Unexpectedly, after infection or induction of allergic asthma, eosinophils are also a chief source of the inflammatory cytokines IL-17 and IL-23, and in fact, under the conditions assessed, they are almost exclusively the producers of IL-23 in the lungs. The main effect of this cytokine secretion is probably to drive the recruitment and/or local proliferation of inflammatory monocytes and lung macrophages. Therefore, in addition to being simply effector cells, lung eosinophils are probably important in shaping the local immune response.

PLoS Pathog. (17 January 2017)