BCR is required for TLR-induced B cell activation. (A) Fraction of control (IgM⁺) and mutant (IgM⁻) B cells that had divided after 72 h of culture with the indicated stimuli; abbreviations of stimuli as in Fig. 1 A. Plots show combined results from three experiments with at least nine replicates for each sample, except for IgM⁻ cells stimulated with CD40L alone, for which there were six replicates. (B) Cell surface expression of CD86 (mean fluorescence intensity [MFI]) on IgM⁺ or IgM⁻ B cells cultured for 24 h with the indicated stimuli; one of two independent experiments with n = 5 and 6 replicates for IgM⁺ and IgM⁻ cells, respectively. Graphs show mean ± SEM. Statistical analysis was performed using a Mann–Whitney test; *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001.