Abnormal subpopulations of peripheral blood lymphocytes are involved in Parkinson's disease

Background: Abnormal immune responses are involved in the development of Parkinson's disease (PD), and also affect peripheral blood lymphocytes. The profile of lymphocyte subsets in peripheral blood and whether it is relevant to the clinical features of PD patients remains controversial. Methods: To explore the role of peripheral blood lymphocytes (NK cells, B cells, CD3+ T cells, CD3+CD4+ T cells and CD3+CD8+ T cells) in the development of PD, a case-control study including 127 patients and 148 healthy controls was conducted, and peripheral blood lymphocyte subpopulations of participants were analysed by a FACSCalibur flow cytometer. Results: PD patients had a significantly higher percentage of NK cells and a lower percentage of CD3+ T cells and CD3+CD4+ T cells than controls [16.4% (12.3%) vs. 12.6% (6.2%), 63.7% (14.2%) vs. 69.0% (6.6%), 33.1% (13.1%) vs. 38.9% (7.6%), P<0.05, respectively]. Through a binary logistic regression model adjusted for gender and age, we found that those who were outside of the reference range of peripheral blood lymphocytes (NK cell, B cell, CD3+ T cell and CD3+CD4+ T cell) had an increased risk of PD [odds ratio (OR): 2.3, 5.1, 3.1 and 4.1, P<0.05, respectively]. Through a multivariable linear regression model adjusted for gender, age and levodopa equivalent daily dose, we found that deviation from the reference range of CD3+CD8+ T cells (regression coefficient=3.474, P=0.015), course of disease (regression coefficient=0.411, P=0.004) and the Non-Motor Symptoms Scale (NMSS) scores (regression coefficient=0.553, P=5.92E-11) had a positive association with the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS)-III score (adjusted R-2=0.364, F=13.004). Conclusions: Abnormal peripheral blood lymphocyte subpopulations have clinical relevance for PD.