IFNG and Parkinson disease: Although nothing is known about the repertoire of cytokines that is secreted by T-lymphocytes infiltrating the PD brain, peripheral T-lymphocytes from PD patients secrete for instance IFN-γ (Sulzer et al., 2017; Kustrimovic et al., 2018) and TNF-α (Kustrimovic et al., 2018).