Fig. 4: Identification of differential cell subsets in human peripheral blood and brain during PD progression.

A, B Scatter plots and bar graphs of flow cytometry demonstrates the percentages of T cells (CD45⁺CD3⁺), B cells (CD45⁺CD3^-CD19⁺) and NK cells (CD45⁺CD3^-/CD16⁺CD56⁺) in the PBMCs of healthy controls (n = 14), PD-Early (n = 26) and PD-Late patients (n = 13–14). C Bar charts show the correlation of the percentage of T cells, B cells and NK cells with HY scores of PD patients. D, E Immunostaining and quantification show the expression of NK cells (CD16⁺ and CD56⁺) in human PBMCs at healthy controls (n = 6), early (n = 4–6) and late (n = 5–6) stages. Green, CD56 and CD16 positive cells; blue, DAPI. Scale bar = 50 μm. Data were presented as mean ± s.d. and analyzed by one-way ANOVA followed by Tukey’s post hoc test. F, G Immunostaining of TH in the amygdala and motor cortex of healthy controls (n = 3 individuals) and PD-Late (n = 5 from 2 patients) human brain sections. Scale bar = 50 μm. Green, TH positive cells; blue, DAPI. Data are presented as mean ± s.d. and analyzed using two-tailed pairwise Student’s t test. H, I Immunostaining and quantification of NK cells in the amygdala and motor cortex of healthy controls (n = 6–8 from 3 individuals) and PD-Late (n = 3–5 from 2 patients) human brain sections. Green, CD56 positive cells; blue, DAPI. Data are presented as mean ± s.d. and analyzed using two-tailed pairwise Student’s t test. J Correlation of NK cells amount with TH intensity in the amygdala and motor cortex of PD-Late patients. *p < 0.05, **p < 0.01, ***p < 0.001, ns represents no significance.