CD4 and amyotrophic lateral sclerosis: While no significant difference was observed in the levels of PD-1 in CD8+T cells between groups (Figure 1A), ALS patients exhibited elevated proportions of PD-1 in CD4+T cells compared to HCs (8.36 [5.63–9.93] vs. 5.15 [3.83–7.09], p = 0.008, Figure 1B; Table 2).