Anti-CD3 mAb treatment reshapes infiltrating T and β cells in the islets in autoimmune diabetes.

Treatment with anti-CD3 monoclonal antibody (mAb) can delay or prevent type 1 diabetes in mice and humans by modulating the immune-mediated destruction of β cells. A single course of treatment may have lasting efficacy, but the mechanisms that account for these prolonged effects, i.e., "operational tolerance," are not clear. Here, we used paired single-cell RNA and T cell receptor sequencing to characterize islet-infiltrating T cells and their counterpart in paired pancreatic lymph nodes from anti-CD3 mAb-treated nonobese diabetic (NOD) mice in remission. We found that after anti-CD3 mAb treatment, T cells that infiltrate the islets are more heterogeneous and have hybrid features including characteristics of T stem cell-like memory and reduced effector function compared with those from untreated prediabetic NOD mice. Autoantigen-reactive CD8+ T cells persist after treatment, but they also show features of stemness and reduced pathogenicity. Our findings describe the reshaping of islet-infiltrating and autoreactive T cells and β cells that lead to operational, but tenuous, tolerance to autoimmune diabetes following anti-CD3 mAb treatment.