Analysis of differentially expressed genes between Treg-T1D and TILT samples showed minor differences within the PRF1+GZMB+CD8+ T cells at day 0, while activation markers such as PRF1, CD69, and HLA-DRA were upregulated in the TILT patient samples by day 7, after the first course of IL-2 (Figure 6, B and C). The gene discussed is PRF1; the disease is type 1 diabetes mellitus.