IFNG and Parkinson disease: Peripheral populations of Teffs were significantly decreased in PD, possibly due to trafficking to the CNS.11,13,70 Interestingly, the decreased population of Teffs express increased pro-inflammatory transcripts such as tnf, ifnγ, rorc, and tbx21. These signatures are indicative of a Th1 and Th17 pro-inflammatory polarization of T cells.