In the murine SLE models, CD11c+T-bet+ ABC cells are required for antichromatin Ab production (52, 71), and targeted disruption of the Tbx21 gene encoding T-bet abrogates ABC cell production, IgG2a/c expression, and autoantibody production in autoimmune prone strains (39, 43, 71, 72). The gene discussed is ITGAX; the disease is systemic lupus erythematosus.