Objective: To observe express of B7-1(CD80) and B7-2(CD86) in peripheral blood from rats with collagen-induced arthritis (CIA) treated by Scorpio-Scolopendra. Method: Sixty female Wistar rats were randomly divided into 6 groups

the normal control group

the model control group

the low-dose

the middle-dose and the high-dose Scorpio-Scolopendra group(1∶1)

and the type Ⅱcollagen group. Rat arthritis model was induced by injection of collagen. The number of CD80+ and CD86+cell in peripheral blood was tested by flow cytometry. Result: Compared with the model groups

the level of CD80+ cell(55.7±6.31)% was decreased obviously in the middle and low dose of Scorpio-Scolopendra groups (46.6±6.34

30.8±15.14)%(P<0.05). While the level of the CD80+CD86- cell (43.7±10.26)%in peripheral blood from rats in the model groups was higher than in the low dose of Scorpio and Scolopendra group(25.3±12.67)% (P<0.05). Conclusion: The mechanism of Scorpio and Scolopendra treated RA is likely to down-regulate express of B7-1(CD80) and B7-2 (CD86) in peripheral blood.