We further investigated these CD8+CD20+ T cells in the peripheral blood of RO donors by flow cytometry, and found no difference in the frequency of CD8+CD20+ T cells (gated on CD3+CD19− cells, see ESM Fig. 4) between RO type 1 diabetes and ND donors (Fig. 6c, d). This evidence concerns the gene CD19 and type 1 diabetes mellitus.