title: A hidden residential cell in the lung.
abstract: Eosinophils are classically known as proinflammatory cells, as they are equipped with a variety of preformed cytotoxic mediators and have been shown to definitively contribute to asthma. The connection between eosinophils and asthma development has led to a new class of asthma therapeutics based on blocking eosinophils with humanized antibodies that neutralize IL-5, a potent eosinophil growth, activation, and survival factor. Yet, recent studies have led to an increasing appreciation that eosinophils have a variety of homeostatic functions, including immunomodulation. In this issue of the JCI, Mesnil et al. identify a notable population of lung-resident eosinophils and demonstrate that, compared with traditional eosinophils, these cells have distinct characteristics, including nuclear structure, surface markers, IL-5 independence, and immunoregulatory function that is capable of polarizing adaptive immune responses, at least in vitro. Thus, these results reinforce a key homeostatic role for this enigmatic cell population, particularly in residing and regulating immunity in the lung.
authors.forename: Marc E
authors.initials: ME
authors.lastname: Rothenberg
mesh_terms: D001249:Asthma / Q000276:immunology; D004804:Eosinophils / Q000166:cytology*; D015848:Interleukin-5 / Q000276:immunology; D007958:Leukocyte Count; D008168:Lung / Q000276:immunology*
chemical_list: D015848:Interleukin-5