IL25 and helminthiasis: While uncommon in the steady-state, they are both activated and expanded in helminth infection: activation drives release of cysteine leukotrienes, priming ILC2s, which trigger increased differentiation of new tuft cells and associated increases in IL-25 in a feed-forward amplification loop (Gerbe et al., 2016; Schneider et al., 2019) that requires both IL-25 and the pleiotropic cytokine macrophage migration inhibitory factor (Varyani et al., 2022).