Suppression of inflammation by low-dose methotrexate is mediated by adenosine A2A receptor but not A3receptor activation in thioglycollate-induced peritonitis

Table 3 Tumor necrosis factor alpha concentration in peritoneal exudates

	Wild-type mice (pg/ml ± SEM)	A_2A knockout mice (pg/ml ± SEM)	A₃ knockout mice (pg/ml ± SEM)
Control	42 ± 7 (n = 14)	36 ± 8 (n = 10)	75 ± 18* (n = 6)
Methotrexate (0.75 mg/kg/week)	14 ± 4** (n = 15)	25 ± 7 (n = 9)	31 ± 11^† (n = 8)

Wild-type mice, A_2A 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. Tumor necrosis factor alpha 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 A₃ knockout control mice, Student's t test.

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