FIG. 3.

TRAV5D-4 α-chain retrogenic mice develop anti-insulin autoimmunity in response to the native insulin B:9–23 peptide. A, B, and D: Response to insulin B:9–23 peptides. Spleen cells from α-chain retrogenic mice (A: mice expressing an α-chain with TRAV5D-4; B: mice expressing an α-chain with non–TRAV5D-4; D: B16:A double insulin-knockout mice expressing an α-chain with 8–1.1 TRAV5D-4) were tested for response to tetanus toxin peptide 830–843 (open bar), insulin B:9–23 peptide (closed bar), and B16:A B:9–23 peptide (hatched bar) by IFN-γ ELISPOT assay. Data are mean ± SEM and cumulative from equal to or greater than three independent experiments. Stimulation Index >3 (the number of spots in cultures with peptide/without peptide) is considered positive. C: The heat map of IL-2 secretion in response to islets and the insulin B:9–23 peptide by TCR-null CD4⁺ 5KC cell lines expressing β-chain sequences derived from islets of TRAV5D-4 α-chain retrogenic mice along with the original α-chain. Data are mean and are cumulative from two independent experiments. E: The peak value of insulin autoantibodies of 8–1.1 TRAV5D-4 α-chain retrogenic mice with/without native insulin B:9–23 expression. Insulin autoantibodies were measured every 4 weeks between 4 and 16 weeks after bone marrow transplantation. Symbols represent individual mice (wild-type retrogenic recipient mice, n = 9; insulin B:9–23-negative (double insulin-knockout) retrogenic recipient mice, n = 3). IAA index ≥0.01 is defined as positive.