Osteopontin and anti-osteopontin antibodies as potential biomarkers of immune activation in patients with allergic diseases: a comprehensive approach

Rationale: Osteopontin (OPN) is a pleomorphic cytokine known to influence a wide range of immune cells; allergic asthma was previously associated with high circulating OPN levels. The aim was to evaluate OPN as a possible biomarker of immune activation in allergic patients belonging to two different ethnic groups: Caucasians and South-East Asians. B. Method: Serum OPN levels were measured by ELISA test in a series of 121 Italian adult patients affected by allergic asthma, allergic rhinitis, Hymenoptera venom allergy, food allergy, allergic contact dermatitis and IgE-mediated hypersensitivity to B-lactams. 116 healthy subjects served as controls. 576 ethnic Chinese subjects were recruited at the National University of Singapore as cross-sectional cohort of an epidemiological study on the national prevalence of allergic diseases, and OPN levels were detected by Luminex and ELISA assays. C. Results: In the Italian cohort, OPN levels were significantly higher in cases compared to controls (P=0.0010 by the Mann-Whitney test). Statistically higher OPN levels were found in asthma (P=0.0269) and food allergy (P=0.046) groups in comparison to controls. No significant differences were found (P=0.597) between Singaporeans with "lifetime asthma" (i.e., subjects presenting asthma at least once in their life) and healthy controls. However, a strong gender effect was shown, in both cases (P<0.0001) and controls (P