Innate Immune Function of T(H)2 Cells in vivo

Type 2 helper T (T(H)) cells produce interleukin 13 (IL-13) when stimulated by papain or house dust mites (HDM) and induce eosinophilic inflammation. This innate response is dependent on IL-33 but not T cell antigen receptors (TCRs). While type 2 innate lymphoid cells (ILC2s) are the dominant innate producers of IL-13 in naïve animals, we show here that in helminth-infected mice, T(H)2 cell numbers increased and became major mediators of innate type II responses. T(H)2 cells made important contributions to HDM-induced antigen–non-specific eosinophilic inflammation and protected mice recovering from Ascaris suum infection against subsequent infection with the phylogenetically distant nematode Nippostrongylus brasiliensis. Our findings reveal a previously unappreciated role of effector T(H)2 cells during TCR-independent innate-like immune responses.