The role of the immune system in Parkinson disease (PD) has perplexed multiple researchers. Supporting evidence for an association includes the presence of inflammatory cells (reactive microglia) in the substantia nigra in PD autopsies1 and in animal models of PD.2 Also, the association of nonsteroidal anti-inflammatory drug use, and more specifically ibuprofen, with a reduced risk for PD supports the association between inflammation and PD.3 Given the possible link between PD and inflammation and the readily available assays of plasma and serum inflammatory markers, multiple studies have compared plasma and serum concentrations of different cytokines in patients with PD and controls, with conflicting results.
Alcalay RN. Cytokines as Potential Biomarkers of Parkinson Disease. JAMA Neurol. 2016;73(11):1282-1284. doi:10.1001/jamaneurol.2016.3335