PRF1 and type 2 diabetes mellitus: We also observed that the production of circulating TNF-α+ CD4+, TNF-α+ CD8+, TNF-α+ Vδ2+, TNF-α+ Vδ1+, IFN-γ+ CD8+, and IFN-γ+ Vδ2+ T cells was significantly increased compared to that in healthy donors, while granzyme B and perforin levels were not significantly changed in T2D (Figure 1B, Figure S1B-D).