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P.85 THE P2X7 RECEPTOR IS SHED INTO CIRCULATION AND CORRELATES WITH C-REACTIVE PROTEIN LEVELS A.L. Giuliani 1 , M. Berchan 1 , J.M. Sanz 1 , S. Alessio 1 , V. Vultaggio-Poma 1 , A.C. Sarti 1 , S. Pizzicotti 2 , A. Roman 1 , M. Tonegato 1 , A. Passaro 1 and F. Di Virgilio 1 1 University of Ferrara, Ferrara, Italy, 2 S. Anna Hospital, Ferrara, Italy The P2X7 receptor (P2X7R) is an ATP-gated cation channel involved in several disease conditions, inflammation included (1). P2X7R activation determines NLRP3- inflammasome-mediated IL- 1β release, T lymphocytes proliferation and differentiation, and release of microvesicles/microparticles (MVs/MPs) loaded with different molecules, P2X7 subunits too. Some inflammatory membrane receptors (e.g., IL-1R, TNFR, IL-2R) shed under various pathophysiological conditions. To date, there are no measurements of a shed form of P2X7R (sP2X7R) which might be present in blood and whose levels might be associated to inflammation. Here we tested sP2X7R using an ELISA kit (Cusabio) (expressed as means ± SE) or SDS-PAGE and Western Blot (WB). Serum samples were obtained from 26 healthy controls and from 87 patients admitted at our Hospital and stratified into four sub- groups according to diagnosis at admission: infective diseases (n=42), cancer (n=16), ischemic diseases (n=10) and others (trauma and autoimmune diseases) (n=19). Serum or plasma samples were analyzed by ELISA. MVs/MPs-enriched pellets, obtained by ultracentrifugation of serum or plasma samples, and MVs/MPs-deprived plasma/serum were analyzed by ELISA or SDS-PAGE and WB. Supernatants from BzATP-stimulated Ficoll gradient-separated peripheral blood monocytes from 4 healthy subjects were tested by ELISA. In healthy subjects, blood sP2X7R ranged from 16.74 to 82.17 ng/L (40.97±3.82). In patients, blood sP2X7R levels correlated to those of the inflammatory marker C reactive protein (CRP). sP2X7R ranged from 33.1 to 484.0 ng/L (114.78±12.22, n=45) in patients with CRP<3 mg/L, and from 63.65 to 1092.3 ng/L (204.2±30.94, n=42) in patients with CRP>3 mg/L. In the four sub-groups, a positive CRP-sP2X7R correlation was found. In addition, both CRP and sP2X7R were significantly higher in the infective disease patients versus the other three sub-groups. In plasma/serum, sP2X7R was partially associated to MVs/MPs. sP2X7R was present in supernatants of peripheral blood monocytes stimulated with BzATP. In conclusion, the P2X7R has been found shed into circulation, and its blood levels are increased in various inflammatory disease conditions (2). A possible application of sP2X7R as diagnostic/prognostic inflammatory marker is therefore suggested.