IL-25–elicited MPP^type2 cells promote Th2 cytokine–dependent responses in vivo. C57BL/6 WT mice (The Jackson Laboratory) were treated i.p. with 0.3 µg IL-25 daily for 7 d. MLNs were harvested, and MPP^type2 cells were sort-purified and injected intradermally into naive C57BL/6 WT mice. (a) IL-4, IL-5, and IL-13 cytokine production from skin-draining LN cells from mice receiving intradermal injection of control or IL-25–elicited MPP^type2 cells after 48-h αCD3/αCD28 stimulation measured by ELISA. Data in a are representative of two independent experiments. (b–f) C57BL/6 WT mice were treated i.p. with 0.3 µg IL-25 daily for 7 d. MLNs were harvested, and MPP^type2 cells were sort-purified and injected into T. muris–infected (INF) Il17rb^−/− mice (Charles River). (b) IFN-γ cytokine production by T. muris antigen–stimulated MLN cells. (c) Total serum IgE antibody titers measured by ELISA. (d) Periodic acid–Schiff/Alcian blue–stained colon sections of intestine tissue from naive or infected WT or Il17rb^−/− mice ± MPP^type2 cells. N, naive (inset). Bars, 100 µm. (e) Goblet cell counts from d. (f) Worm burdens from T. muris–infected mice were assessed at day 21 after infection. Data in b–f are representative of two independent experiments (WT naive, n = 2–3; WT INF, n = 6–8; Il17rb^−/− naive, n = 2–3; Il17rb^−/− INF, n = 6–7; Il17rb^−/− INF + MPP^type2 cells, n = 6). *, P < 0.05; ***, P < 0.001. IFN-γ production between Il17rb^−/− INF and Il17rb^−/− INF + MPP^type2 cells, P = 0.068. Error bars indicate SEM.