Reduced spleen size, splenocyte number, and the early stage serum autoantibody titers in the absence of IRF7. (A–F) Spleen size (A), weight (B), and splenocyte number (C) in 4-mo-old FcγRIIB^−/− and FcγRIIB^−/−IRF7^−/− (n = 5 mice per group) mice. dsDNA-, nucleosome-, and Sm/RNP-specific serum IgM (D), IgG (E), and IgG2c (F) titers were measured in 2-mo-old FcγRIIB^−/− (n = 8) and FcγRIIB^−/−IRF7^−/− (n = 9) mice by ELISA. Each symbol represents an individual mouse, and data are presented as means ± SEM. P values were calculated via an unpaired Student’s t test or Mann–Whitney test (NS, not significant; *, P < 0.05; **, P < 0.01; ***, P < 0.001).