Objective: To explore the mechanism of Qili Xiaoying decoction on NOD.H-2h4 mice with autoimmune thyroiditis (AIT) in view of CD4+T cell subsets. Method: Sixty SPF NOD.H-2h4 mice were randomly divided into four groups

the normal control group(NC)

the model control group(MC)

the Qili Xiaoying decoction group(ZY1

20.8 g·kg-1) and the 3 times dose of Qili Xiaoying decoction group(ZY3

62.4 g·kg-1).The NC group received sterile water

and the others were administrated with 0.05% NaI for 8 weeks to induce AIT. All mice were sacrificed at the time point of giving treatment factors for 8 weeks.The serum triiodothyronine(TT3) and thyroxine(TT4) were detected by RIA method

the serum thyroid-stimulating hormone(TSH) by IRMA. Thyrocyte morphology was observed under optical microscopy. Immunohistochemistry staining was conducted to analyze the expression of INF-γ and IL-4.The expression of INF-γ mRNA and IL-4 mRNA in NOD.H-2h4 mice thyroid was detected by Real-time (RT ) -PCR

and the Foxp3 expressions in the NOD.H-2h4 mice thyroid were determined by Western blot. Result: ① No apparent differences among every group in serum TT3

TT4 and TSH were found.②Lymphocytic infiltration could be found by HE staining

AIT occurrence rate of MC was obviously higher than the NC(P<0.01).③ Compared with the NC group

expression of INF-γ mRNA

IL-4 mRNA and protein in the MC decreased markedly(P<0.01);compared to the MC

the protein expression of INF-γ and IL-4 both in ZY1 and ZY3 were increased (respectively P<0.01

P<0.05). The expression of INF-γ mRNA and IL-4 mRNA in ZY1 and ZY3 were also increased remarkably(P<0.01).④ The protein expressions of Foxp3 in the MC declined markedly compared with the NC (P<0.01); the Foxp3 expression in ZY1 and ZY3 ascended remarkably compared with the MC(P<0.01). Conclusion: The therapeutic mechanism of Qili Xiaoying decoction on NOD.H-2h4 with AIT may be related to influencing the cell subsets of Th1

Th2

Treg by up-regulating the expression of INF-γ

IL-4 and Foxp3.