TNF and Parkinson disease: Several lines of research have shown that serum oxidative stress and pro-inflammatory cytokines such as interleukin (IL)-1b, IL-2, IL-6, HLA-DRB1, phospholipase A(2), tumor necrosis factor (TNF)-a, and TNF-a receptors are elevated in the brain and cerebral spinal fluid of PD patients [1], [2], [3], [4].