Objective: To investigate part mechanisms of Th cell differentiation, and to observe the interference effect of Qingxin-Ⅱ Recipe in the chronic stage of viral myocarditis (VMC), so as to provide some experimental evidences for illuminating the pathogenesis of VMC and treatment mechanisms of Qingxin-ⅡRecipe.Methods: According to 20%-40% death rate of experiment in advance, 100 BALB/c male mice (4 weeks old and weighing 12-15 g) were used. Twenty mice were randomly assigned to normal control group, and the other 80 mice were intraperitoneally injected with 0.1 ml normal saline containing coxsackie virus B₃ at the 1st, 4th and 28th day (the virus densities were 1∶2 000, 1∶1 000 and 1∶500 respectively) to induce chronic VMC. At the 42nd day, the surviving mice were randomly divided into untreated group and treatment group, with 20 mice in each group. Mice in the treatment group were orally administered with 0.2 ml Qingxin-Ⅱ Recipe every day, while mice in the normal control group and the untreated group were administered with 0.2 ml normal saline. All the mice were sacrificed after 45 days, and the sera, heart and spleen cells were collected. Then the myocardial pathological changes were observed by using a light microscope, and the levels of IL-4, IL-10 and IFN-γ in serum were detected by enzyme linked immunosorbent assay (ELISA). And the Th cell differentiation was observed by flow cytometry.Result: No obvious myocardial pathological changes were observed in mice of the normal control group. Myocardial pathological changes in the treatment group were slighter than those in the untreated group. The difference of serum IL-10 level between the normal control group and the untreated group showed no significance (P>0.05), and the levels of IFN-γ and IL-4 of the untreated group were higher than those of the normal control group (P＜0.05 or P＜0.01). There was no statistical difference in IL-10 level between the treatment group and the untreated group (P>0.05), while the serum levels of IL-4 and IFN-γ of the treatment group were lower than those of the untreated group (P＜0.05 or P＜0.01). There was no significant difference of the Th1 cell responder between the treatment group and the untreated group (P>0.05), while the Th2 cell responder was inhibited significantly in the treatment group (P＜0.05).Conclusion: Qingxin-Ⅱ Recipe can restore the balance of Thl and Th2 cells through inhibiting the reaction of Th2.

Key words: myocarditis, viruses, cell differentiation, pathology, mice