A cross-sectional exploration of the relationship between Parkinson's disease and peripheral blood immune cells in an ethnically diverse East London population.

BACKGROUND/

OBJECTIVES

Parkinson's disease patients (PD) display changes in the levels of circulating peripheral immune cells. A declining lymphocyte count and a raised neutrophil-to-lymphocyte ratio (NLR) may result from an impaired adaptive response and increased levels of inflammation. This study sought to identify circulating peripheral immune cell changes in PD patients.

METHODS

PD and healthy controls (HC) were recruited from the East London Parkinson's Disease (ELPD) project. Numbers of immune cells from peripheral blood samples were cross-sectionally analysed across three (pre-, within 6 months of PD diagnosis, and post-PD diagnosis) or two (pre- and post-PD diagnosis) time points and compared with HC.

RESULTS

The study included 145 (85 male (M), 60 female (F)) PD and 73 (47 M, 26 F) HC. The two-time point analysis included all participants, whereas the three-time point analysis included 41 (25 M, 16 F) PD and 55 (36 M, 19 F) HC. Lymphocyte count and NLR were not significantly different between PD and HC. There was a non-significant trend towards lower lymphocyte count in PD following diagnosis in an unadjusted model for both the two-time point (OR = 0.76; CI = 0.56-1.02, p = 0.069) and three-time point (OR = 0.62; CI = 0.37-1.30, p = 0.064) analyses, but in both analyses this trend disappeared when adjusting for confounding factors. Levodopa equivalent daily dose was not significantly associated with lymphocyte count or NLR.

CONCLUSION

Our study revealed no significant difference in lymphocyte count or NLR between PD and HC. There was a non-significant trend towards lower lymphocyte count following diagnosis in PD.