Objective:To study the effect of dihydroartemisinin on immune-regulation of T-lymphocytes from peripheral blood in adjuvant-induced arthritis（AA） rats.Method: Sprague Dawley rats with a mean weight of 160-180 g were randomly divided into 6 groups

including normal group

AA model group

methotrexate group（1 mg · kg-1）

dihydroartemisinine high-dose

medium-dose and low-dose group（11.2

5.6

2.8 mg ·kg-1）.The rat adjuvant arthritis model were induced.The drugs were administrated by ig for consecutive 28 days after inducing AA model.T-lymphocyte in peripheral blood was detected by flow cytometry

and the levels of interferon-γ（INF-γ） and interleukin-4（IL-4） in serum were measured by ELISA on AA animal model treated bydihydroartemisinin.Result: Compared with the normal group

the ratio of CD4+T

CD4+T/ CD8+T from peripheral blood in model group and IFN-γ levels in serum were significantly increased（P<0.01）

and the levels of IL-4 were significantly decreased（P<0.01）.In high and medium dose group

the percentages of CD4+T was（34.81±3.80）%

（34.92±5.14）%

the ratio of CD4+T/ CD8+T was 2.21±0.43

2.27±0.48

respectively

compared with model group they were significantly decreased（P<0.05

P<0.01）.In dihydroartemisinin three dose group

the levels of INF-γ were（15.90±2.05）

（16.27±2.11）

（18.15±2.15） ng·L-1

and the levels of IL-4 were（40.21±4.89）

（40.04±4.56）

（34.81±4.02） ng·L-1

compared with the model group they had significant changes（P<0.01）.For IL-4

dihydroartemisinin’s effect showed a dose-dependent manner at concentrations between 2.8-5.6 mg · kg-1（P<0.05）.Conclusion:Dihydroartemisinin could effectively improve the immunity mess in T-lymphocytes from peripheral blood in AA rats

which is useful for curing rheumatoid arthritis.