Serum IL-33 but not ST2 level is elevated in intermittent allergic rhinitis and is a marker of the disease severity

Th2 cells play an important role in intermittent allergic rhinitis (IAR). Interleukin (IL)-33 stimulates the production of Th2-associated cytokines. IL-33 binds to ST2 receptor which is highly expressed on mast cells and selectively on Th2 cells. IL-33 and ST2 might be involved in the Th2-mediated immune response. We analyzed the serum level of IL-33 and its receptor ST2 in patients with IAR sensitive to grass and/or tree pollen to assess if the serum level of IL-33 and/or ST2 may be a marker of the disease severity. IL-33, ST2 and total immunoglobulin (Ig) E were measured in sera of patients with IAR sensitive to birch and/or grass pollen and in patients with controlled bronchial asthma and in non-allergic controls. IAR severity was assessed by total nasal symptom score. Serum levels of IL-33 in patients with IAR were comparable with patients with bronchial asthma and were significantly higher in patients with IAR ( = 0.0035) and in patients with bronchial asthma ( = 0.008) than in controls. Serum levels of IL-33 correlated with disease severity. Elevated level of IL-33 in sera of patients with IAR sensitive to tree and/or grass pollen and the correlation of IL-33 with the disease severity suggest that IL-33 is involved in the pathogenesis of intermittent allergic rhinitis.