CD19 and Parkinson disease: We identified a significant decrease in the percentage of B cells. Significantly higher proportions of regulatory B (CD19+ CD5+ IL-10+ and CD19+ CD5+ FoxP3+)cells were detected in patients with PD than in controls. Compared to baseline, we also observed a decrease in the percentage of regulatory B cells (CD19+ CD5+ IL-10+), whereas the proportion of B cells (CD19+) increased.