Silencing of high-affinity insulin-reactive B lymphocytes by anergy and impact of the NOD genetic background in mice

Abstract

Aims/hypothesis: Previous studies have demonstrated that high-affinity insulin-binding B cells (IBCs) silenced by anergy in healthy humans lose their anergy in islet autoantibody-positive individuals with recent-onset type 1 diabetes, and in autoantibody-negative first-degree relatives carrying certain risk alleles. Here we explore the hypothesis that IBCs are found in the immune periphery of disease-resistant C57BL/6-H2g7 mice, where, as in healthy humans, they are anergic, but that in disease-prone genetic backgrounds (NOD) they become activated and migrate to the pancreas and pancreatic lymph nodes, where they participate in the development of type 1 diabetes. Methods: We compared the status of high-affinity IBCs in disease-resistant VH125.C57BL/6-H2g7 and disease-prone VH125.NOD mice. Results: Consistent with findings in healthy humans, high-affinity IBCs reach the periphery in disease-resistant mice and are anergic, as indicated by a reduced expression of membrane IgM, unresponsiveness to antigen and failure to become activated or accumulate in the pancreatic lymph nodes or pancreas. In NOD mice, high-affinity IBCs reach the periphery early in life and increase in number prior to the onset of hyperglycaemia. These cells are not anergic; they become activated, produce autoantibodies and accumulate in the pancreas and pancreatic lymph nodes prior to disease development. Conclusions/interpretation: These findings are consistent with genetic determination of the escape of high-affinity IBCs from anergy and their early contribution to the development of type 1 diabetes.