Fig. 4. Patients with T1D have fewer CD8⁺ Treg cells compared with healthy volunteers.

Evaluation of CD8⁺ Treg cells and microbiota in T1D patients (N = 15) and healthy volunteers (N = 16) was performed. a Peripheral blood mononuclear cells obtained from T1D patients were stained with fluorescent dye-labelled anti-CD8, anti-CXCR3, and anti-CD122 antibodies. CXCR3⁺ cells among gated lymphoid cells (left and centre panels) were separated into CD8⁺ and CD122⁺ (right panels). The numbers indicate the percentages of gated cells. b Frequency of CD8⁺ Treg cells defined as CXCR3⁺CD8^dullCD122⁺ cells in T1D patients and healthy volunteers is plotted as a scatter graph with bars. c Composition of the intestinal microbiota in T1D patients and healthy volunteers at the family level. d Frequency of genus Ruminococcus in whole intestinal bacteria. e Trehalose concentration in serum from T1D patients and healthy volunteers. Values represent the mean ± SD. f Representative co-plotted frequency of CD8⁺ Treg cells, abundance of Ruminococcus, and trehalose concentration in T1D patients and healthy volunteers. R² denotes the correlation coefficient. p-values were calculated using the two-tailed Mann–Whitney test (b, d, e). All experiments using human samples were performed once.