Abstract: Objective To observe the effect of X-rays irradiation on IL-18 expression in mouse peritoneal macrophages. Methods Eiyghty Kunming white mice were divided into 10 groups(eight each group) : sham-irradiation, four groups of low-dose irradiation (0.05，0.075， 0.1 and 0.2 Gy), and five groups of high-dose irradiation (0.5，1.0，2.0，4.0 and 6.0 Gy). The mice were killed 16 h after whole body irradiation(WBI), with X-rays then the peritoneal macrophages were obtained and cultivated with culture medium of RPMI 1640 in culture box with 37℃，5％ CO₂ for 72 h. The supernate was gathered to detect the IL-18 expression level in macrophages by ELISA. Results The IL-18 expresson level in sham-irradiation group was (51.29±3.26 )ng•L^-1, IL-18 expression was enhanced after 0.05 Gy WBI, but there was no significant difference (P＞0.05）. The expression level was increased to (122.78±8.07) ng•L^-1 after 0.075 Gy WBI, and there was significant difference compared with sham-irridiation group(P<0.01). IL-18 expression was increased gradually with the enhancement of X-rays irradiated doses　（0.1， 0.2，0.5 and 1.0 Gy), and the values were (135.32±5.27)，(149.40±16.54)，(200.42±15.42)and(347.59 ±17.88)ng•L^-1, respectively. It peaked after 1.0 Gy irradiation, then it decreased after 2.0，4.0 and 6.0 Gy irradiation, and the values were (229.49±14.68)，(253.79±6.69) and (223.32±20.85 )ng•L^-1, respectively, but they were higher than that in sham-irradiation group(P<0.01). Conclusion Both high-dose and low-dose X-rays irradiation can stimulate IL-18 expression in mouse peritoneal macrophages.

Key words: macrophages, interteukin-18