CD19 and Parkinson disease: Frequencies of CD3+ T cells (79.40 ± 1.201 vs. 77.81 ± 1.331), CD4+ helper T cells (52.06 ± 2.259 vs. 53.05 ± 2.430), CD8+ cytotoxic T cells (33.57 ± 1.875 vs. 31.39 ± 1.932), CD19+ B cells (5.805 ± 0.4360 vs. 5.651 ± 0.5065) and CD16/56+ NK cells (11.06 ± 1.17 vs. 14.31 ± 1.12) were comparable between PD and control groups.