Methods: Serum OPN levels were measured by ELISA test (Human Osteopontin Duoset, R&D Systems, for OPN detection; “in-house” kit for anti-OPN AutoAbs). A series of 121 adult patients affected by asthma, allergic rhinitis (AR), Hymenoptera venom allergy (HVA), food allergy (FA), allergic contact dermatitis (ACD) and IgE-mediated hypersensitivity to beta-lactams (IEHB) was studied. 116 healthy subjects served as controls.
Results: OPN serum levels were significantly higher in cases in comparison to controls (p=0.0010 by the Mann-Whitney test). Statistically higher levels were found in asthma (p=0.0269) and FA (p=0.046) groups in comparison to controls. Prevalence and titers of serum IgG anti-OPN AutoAbs were significantly lower in cases with respect to controls (p<0.0001). Lower levels of AutoAbs versus controls were found in patients with HVA (p<0.0001), AR (p=0.0009), ACD (p=0.0011) and asthma (p=0.0013), but not in FA group (p=0.0575). Patients with IEHB presented heterogeneous results for OPN and anti-OPN AutoAbs.
Conclusions: Serum OPN levels may represent a novel, potentially useful biomarker for allergic asthma and, interestingly, for food allergy.