Wild-type mice, A2A receptor knockout mice or A3 receptor knockout mice were treated with either weekly injections of methotrexate (0.75 mg/kg) or saline control for 4 weeks prior to induction of inflammation. Inflammatory exudates were induced in the peritoneum of mice, as described. After 4 hours the exudates were collected, centrifuged at 100 × g and frozen. IL-10 levels were later quantitated by ELISA. Wild-type data are a combination from both mouse strains. ** P < 0.001 vs wild-type control mice, Student's t test; * P < 0.05 vs wild-type control mice, Student's t test; †P < 0.05 vs A2A knockout control mice, Student's t test.