In this regard, plasma level IL-2, IL-4, IL-18, IFN-γ, TNF-α, and GM-CSF were increased in the PD group compared with those of controls (Table 1), while that of IL-1β (p = 0.01) and IL-12p70 (p = 0.01) between PD and controls did not reach the statistical difference. Here, IL2 is linked to Parkinson disease.