CD27 and Parkinson disease: Meanwhile, TCM (CD45RO+CCR7+CD27+) and transitional memory (TM) (CD45RO+CCR7-CD27+) CD8 T cells were reduced (Supplementary Fig. 3D, E), while naive (CD45RO−CCR7+CD27+) CD8 T cells showed no difference between PD and HC (Supplementary Fig. 3F).