Serum IL-9 levels and sublingual immunotherapy: preliminary report.

Th9 is a new T cell subset characterized by IL-9 production. It has been reported that serum IL-9 levels are related with symptom severity in patients with allergic rhinitis (AR). This study is aimed at investigating whether serum IL-9 may be modulated by sublingual immunotherapy (SLIT) in patients with persistent AR due to Parietaria allergy. Twenty-one AR patients (9 males, median age 41 years) successfully treated with SLIT and 52 AR patients (25 males, median age 34 years) treated only with drugs were evaluated during the pollen season. Serum IL-9 was dosed in all patients. SLIT-treated patients showed significantly lower serum IL-9 levels than untreated AR patients (p <0.0001). In conclusion, this preliminary study shows that a single pre-seasonal SLIT course might modulate serum IL-9.