Eosinophils and Th2 immunity: contemporary insights

Eosinophils, innate immune leukocytes elicited by Th2 cells, have long been associated with the effector arm of Th2 immune responses. However, accumulating data over the past decade reveal a much more dynamic picture of Th2 immunity, where eosinophils are present very early in response to Th2-inducing agents and function in the initiation of Th2 immunity. Here we discuss recent data showing immune functions of eosinophils distinct from their previously appreciated tissue- and helminth-destructive capacities, providing strong evidence for a new paradigm of Th2 immunity defined by a dynamic interplay between eosinophils and T cells.