Neutrophils in Homeostasis, Immunity, and Cancer

Neutrophils were among the first leukocytes described and visualized by early immunologists. Prominent effector functions during infection and sterile inflammation classically placed them low in the immune tree as rapid, mindless aggressors with poor regulatory functions. This view is currently under reassessment as we uncover new aspects of their life cycle and identify transcriptional and phenotypic diversity that endows them with regulatory properties that extend beyond their lifetime in the circulation. These properties are revealing unanticipated roles for neutrophils in supporting homeostasis, as well as complex disease states such as cancer. We focus this review on these emerging functions in order to define the true roles of neutrophils in homeostasis, immunity, and disease.We acknowledge funding from MINECO (SAF2015-65607-R, SAF2013-49662-EXP and PCIN-2014-103 to A.H; SVP-2014-068595 to J.A.N.-A.; and BES-2013-065550 to J.M.A). The CNIC is supported by the MINECO and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505).S