When comparing the provisional tic disorder group, chronic motor or vocal tic disorder group and Tourette syndrome group with the control group respectively, the average serum level of IL-2 (p = 0.00, Figure 2A), IL-4 (p = 0.00, Figure 2B), IL-10 (p = 0.00, Figure 2D), TNF-α (p = 0.00, Figure 2E) and IFN-γ (p = 0.00, Figure 2F) in these three groups of tics were significantly lower than that of the control group, while the average concentration of IL-6 (p = 0.00, Figure 2C) was significantly higher. Here, IL2 is linked to Tourette syndrome.