On a sensitive electrochemiluminescence-based platform (Quickplex, Meso Scale Discovery®), we examined a panel of C-reactive protein (CRP) and eight selected cytokines, IFN-γ, IL-10, IL-18, IL-1β, IL-4, IL-6, TGF-β1, and TNF-α, among patients with PD (n = 46), MSA (n = 35), and PSP (n = 39) or controls (n = 31). The gene discussed is IL4; the disease is Parkinson disease.