Naive T cells sense the cysteine protease allergen papain through protease-activated receptor 2 and propel TH2 immunity

These results elucidate a novel innate allergen-recognition pathway mediated by naive T cells through PAR2, which provide an immediate source of chemokines and IL-4 upstream of basophils and antigen-restricted TH2 differentiation. PAR2 antagonism might thus hold promise for the treatment of allergic disease.