Serum immunoglobulin levels and antibody responses to TNP-Ficoll in TACI transgenic mice. (A) Serum IgA, IgG, and IgM levels from nonimmunized 8- to 12-week-old TACI^+/+, TACI^−/−, and TACI transgenic mice. The median (center line), 25th to 75th percentiles (box), and lowest and highest values (bars) are shown for each (n = 10-12 mice per group). (B) IgM and IgG anti-TNP antibody responses 14 days after immunization. Bars represent the standard error (n = 10-12 mice per group). For IgG anti-TNP, the lines representing A144E and TACI^−/− groups are overlapping. The Mann-Whitney test was used in panel A, and 2-way ANOVA was used in panel B to calculate significance. (*P < .05, **P < .01, ***P < .005.)