Dimensions of neutrophil life and fate

The earliest reported observations on neutrophils date from 1879 to 1880, when Paul Ehrlich utilized a set of coal tar dyes to interrogate differential staining properties of the granules from white blood cells. While acidic and basic dyes identified eosinophils and basophils respectively, neutrophils were revealed by neutral dyes. Unknowingly, his work staining blood films set the stage for one of the most exciting features of immune cells discovered in the last decade, myeloid heterogeneity. Since then, advances in live imaging and high-resolution sequencing technologies have revolutionized how we analyze and envision those cells that Ehrich fixed in blood smears. Neutrophil plasticity and heterotypic interactions with immune and non-immune compartments are increasingly appreciated as an important part of their biology. In this review, we highlight early and recent work that will help the reader to appreciate our current view of the neutrophil life cycle -from maturation to elimination-, and how neutrophils behave and dynamically modulate tissue immunity, both in steady-state and in disease.