Figure S1. Identification of IL-17 producing cells. Figure S2. Gating strategy to identify Tregs.

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“Non-obese diabetic (NOD) mice lacking interleukin (IL)-21 or IL-21 receptor do not develop autoimmune type 1 diabetes (T1D). We have shown recently that IL-21 may promote activation of autoreactive CD8+ T cells by increasing their antigen responsiveness. To investigate the role of IL-21 in activating diabetogenic CD8+ T cells in the NOD mouse, we generated IL-21-deficient NOD mice expressing the highly pathogenic major histocompatibility

complex (MHC) class-I-restricted 8.3 CX-4945 transgenic T cell receptor (TCR). IL-21 deficiency protected 8.3-NOD mice completely from T1D. CD8+ T cells from the 8.3-NOD.Il21−/− mice showed decreased antigen-induced proliferation but displayed robust antigen-specific cytolytic activity and production of effector cytokines. IL-21-deficient 8.3 T cells underwent efficient homeostatic proliferation, and previous antigen stimulation enabled these cells to cause diabetes in NOD.Scid recipients. The 8.3 T cells that developed in an IL-21-deficient environment showed impaired antigen-specific proliferation in vivo even in IL-21-sufficient mice. These cells also showed impaired IL-2 production and Il2 gene transcription following antigen stimulation. Selleck Galunisertib However, IL-2 addition failed to reverse their impaired proliferation completely. These findings indicate that IL-21 is required for efficient initial activation of autoreactive CD8+ T cells but is dispensable for the activated cells to develop effector functions and cause disease. Hence, therapeutic targeting of IL-21 in T1D may inhibit activation of naive autoreactive CD8+ T cells, IKBKE but may have to be combined with other strategies

to inhibit already activated cells. Non-obese diabetic (NOD) mice develop spontaneously autoimmune insulin-dependent type 1 diabetes (T1D), which shares many disease characteristics with human T1D. Susceptibility or resistance to T1D is determined genetically by several insulin-dependent diabetes (Idd) loci. The Idd3 locus encompasses a 650 kb region on chromosome 3 and contains genes encoding interleukin (IL)-2 and IL-21 [1, 2]. In the NOD mouse, polymorphisms at the Il2 gene promoter and decreased transcription and stability of IL-2 mRNA are implicated in reduced IL-2 production, which has been correlated with reduced frequency and functions of CD4+CD25+ regulatory T cells (Tregs) [1, 3, 4]. The ability of the C57BL/6-derived Idd3 locus to protect NOD mice from insulitis and diabetes has been correlated with reduced IL-21 mRNA and protein levels [1, 5, 6].