CD4 and Parkinson disease: As shown through several studies, evidence of the role of neuroinflammation in PD patients are indicative of higher levels of proinflammatory cytokines in serum and cerebrospinal fluid, presence of activated microglia in different CNS areas such as substantia nigra, infiltration of CD4+ and CD8+ T cells in affected brain regions, and modified performance of the cellular immunity for example malfunction in monocytes phagocytosis.