Monocyte-Derived Alveolar Macrophages Mediate Resistance to Migrating Helminths Through Depletion of Arginine Availability

We examined the activation and effector functions of lung macrophages in mediatingimmunity against helminth parasites. Using fate mapping mice, we showed thatmonocytes recruited to the lung assume an alveolar macrophage phenotype andcomprise as many as 10% of alveolar macrophages by 7 days after inoculation.Monocyte-derived alveolar macrophages assume distinct transcriptional and metabolicprofiles that include high levels of arginase expression and preferentially mediatehelminth damage, both of which are dependent on neutrophil help. In further studies,arginase was shown to mediate helminth killing through localized depletion of arginine.