Changes of T lymphocyte subpopulations and their roles in predicting the risk of Parkinson's disease.

T lymphocytes are involved in the pathogenesis of Parkinson's disease (PD), while the heterogeneity of T-cell subpopulations remains elusive. In this study, we analyzed up to 22 subpopulations of T lymphocytes in 115 PD patients and 60 matched healthy controls (HC) using flow cytometry. We found that PD patients exhibited decreased naïve CD8 +  T cells (CD3 +  CD8 +  CD45RA +  CD45RO - ) and increased late-differentiated CD4 +  T cells (CD3 +  CD4 +  CD28 -  CD27 - ), compared to HC, which were not affected by anti-parkinsonism medication administration. The proportion of naïve CD8 +  T cells in PD patients was positively correlated with their severity of autonomic dysfunction and psychiatric complications, but negatively associated with the severity of rapid eye movement and sleep behavior disorder. The proportion of late-differentiated CD4 +  T cells was negatively correlated with the onset age of the disease. We further developed individualized PD risk prediction models with high reliability and accuracy on the base of the T lymphocyte subpopulations. These data suggest that peripheral cellular immunity is disturbed in PD patients, and changes in CD8 +  T cells and late-differentiated CD4 +  T cells are representative and significant. Therefore, we recommend naïve CD8 + and late-differentiated CD4 +  T cells as candidates for multicentric clinical study and pathomechanism study of PD.