Alterations of peripheral blood lymphocyte subsets and plasma cytokines in Parkinson's disease and the parkinsonian subtype of multiple system atrophy

Objective Peripheral immune system plays a crucial role in neurodegenerative diseases, but its alterations in Parkinson's disease (PD) and the parkinsonian subtype of multiple system atrophy (MSA-P) remained unclear. In this study, we investigated alterations of peripheral blood lymphocyte subsets and plasma cytokines among PD patients, MSA-P patients and healthy controls (HCs), and further compared their peripheral immune discrepancies. Methods This observational study collected participants' peripheral venous blood from the Department of Neurology, People's Hospital of Xinjiang Uygur Autonomous Region from May 2025 to August 2026. The overall comparisons of lymphocyte subsets and cytokines among groups were conducted through MANCOVA, and distinguishing ability was tested through 5-fold cross-validated receiver operating characteristic curves and sensitivity analysis. Results One hundred twenty PD patients, 45 MSA-P patients, and 119 HCs were enrolled in this study. MSA-P patients had younger age, younger age of symptom onset, shorter symptom duration, and lower drug dosage compared to PD patients. When PD patients and MSA-P patients had similar clinical performance, the count and percentage of CD4–CD8– T cells and IL-2 were significantly increased in MSA-P patients. And CD4–CD8– T cells exhibited a satisfactory discriminatory capacity to differentiate MSA-P from PD, which had no statistically significant correlation with clinical indicators. Discussion Peripheral blood CD4–CD8– T cells might have the ability to differentiate MSA-P from PD, but relevant conclusions remained to be further verified.