Innate-type and acquired-type allergy regulated by IL-33.

We propose two types of allergic response: IgE-dependent and IgE-independent, and designate these as 'acquired-type allergy' and 'innate-type allergy', respectively. IL-33 stimulates both innate (basophils, mast cells, or group 2 innate lymphoid cells) and acquired (Th2 cells) allergy-related cells to induce and/or augment Th2 cytokine production, which leads to eosinophilic inflammation in vivo. Thus, IL-33 is an essential regulator for both 'innate-type allergy' and 'acquired-type allergy', and might be an attractive therapeutic target for allergic diseases.