Generation of circulating autoreactive pre-plasma cells fueled by naïve B cells in celiac disease

Autoantibodies against the enzyme transglutaminase 2 (TG2) are characteristic of celiac disease (CeD), and TG2-specific IgA plasma cells are abundant in gut biopsies of patients. We here describe the corresponding population of autoreactive B cells in blood. Circulating TG2-specific IgA cells were found in untreated patients on a gluten-containing diet but not in controls. They were clonally related to TG2-specific small intestinal plasma cells, and they expressed gut-homing molecules, indicating that they are plasma cell precursors. Unlike other IgA-switched cells, the TG2-specific cells were negative for CD27, placing them in the double negative (IgD-CD27-) category. They had a plasmablast or activated memory B-cell phenotype, and they harbored fewer variable region mutations than other IgA cells. Based on their similarity to naïve B cells, we propose that autoreactive IgA cells in CeD are generated mainly through chronic recruitment of naïve B cells via an extrafollicular response involving gluten-specific CD4+ T cells. ### Competing Interest Statement The authors have declared no competing interest.