FIG. 5.

In vivo assessment of the autoreactive potential of GAD-autoreactive CD4 T-cells from patient 3. Immunodeficient mice with streptozotocin-induced diabetes were transplanted with human islets (2,000 islets equivalents) from an HLA-A1, A29, B8, B44, DR17(3)/DRX donor, which had been cultured for 24 h, and T-cells purified from blood obtained from patient 3 at 9.5 years of follow-up (sample no. 6, Fig. 3B). Specifically, we purified and cotransplanted islets with 6,000 tetramer-positive, GAD-autoreactive CD4 T-cells (6% of the CD4 T-cells, A). Control diabetic mice received islets and 30,000 CD4 T-cells after stimulation with the OspA control peptide (B) or islets alone (C). There was no response to this negative control peptide. Thus, this was a polyclonal T-cell population, which could have included alloreactive T-cells. CD25 staining confirmed that these T-cells had been activated in vitro (B). On metabolic follow-up (D), both control mice reversed their diabetes after islet transplantation, while the mouse that received the GAD-autoreactive CD4 T-cells remained hyperglycemic for the entire duration of the experiment. Control mice reverted to diabetes when the grafts were removed by nephrectomy (arrow) after ∼2 weeks. H&E stains from the islet-only control mouse showed mostly normal islets with some fibrosis in the surrounding tissue, as sometimes observed in these grafts (C). Insulin and glucagon stains in the same graft area revealed normal immunoreactivity for the islet-only control (C) and in the control mouse that received polyclonal, activated CD4 T-cells (B). However, H&E-stained sections revealed more fibrosis and inflammation, which could have been in part mediated by the polyclonal T-cells. H&E staining revealed severe islet destruction in the graft of the mouse transplanted with GAD-autoreactive CD4 T-cells, and hormone stains highlighted β-cell loss (A). (A high-quality digital representation of this figure is available in the online issue.)