IL-25 is increased in CSS patients and correlates with disease activity and eosinophil count. (A) Quantitative measurement of IL-25 in the serum of active CSS, inactive CSS, atopic, and HES patients and healthy donors. (B) Correlation between serum IL-25 level and eosinophil count in CSS patients. (C) Correlation between serum IL-25 and eosinophil count in undefined HES patients.