Fig. 4

Cognitive and functional declines were associated with diminished CD8⁺ T-cells and status changes in CD25 (IL-2RA) and PD-1. A Following the flow cytometric analysis, the PD-1⁺/PD-L1⁺ T-cell subset amounts were correlated with MMSE-minus and CDR-SOB to investigate the relationship between the immune status and disease progression. B Pearson correlation between CDR-SOB and MMSE/MMSE-minus (Pearson correlation coefficient r = − 0.555, p = 0.026 and r = 0.841, p = 0.000045). C–E Pearson correlation between CD8⁺ T-cell percentage and CDR-SOB (r = − 0.509, p = 0.044), between CD8⁺CD25⁺ T-cell percentage and MMSE-minus (r = − 0.588, p = 0.016), and between PD-1⁺CD8⁺ T-cell percentage and CDR-SOB (r = − 0.600, p = 0.014)