MSU crystals were prepared with 500 ml of boiling water and 2 g of uric acid (U2625, Sigma Aldrich). pH solution was maintained at 8 by adding NaOH (1 M). Solution was cooled and kept 24 hours during crystals formation. Crystals were filtered in 100 µm sieve before washing in ethanol and warm sterilization. Peritonitis was induced in 8-weeks old WT and CalpTG females by intraperitoneal (I.P.) injection of 3 mg MSU diluted in 0.5 ml PBS. After 3 hours, peritoneal cavity was flushed with 3 ml PBS heparin for 3 mn. Peritoneal fluid was centrifugated at 4 °C and supernatant has been analyzed by ELISA for Interleukine 1 α (Il-1α) and β (Il-1β) (MLA00, MLB00C, R&D systems).