GpG-ODN induces a Th2 B cell response. (A) Purified splenic B cells (derived from animals analyzed in Experiment 1) were stimulated in vitro with anti-IgM, anti-CD40, or anti-IgM plus anti-CD40, and proliferation was assessed after 48 h in culture. Results are expressed as a stimulation index (mean cpm in presence of stimulus ÷ mean cpm without stimulus). Symbols indicate statistically significant values as follows: For the CpG-ODN group, +p < 0.05 (vs. PBS group, anti-IgM stimulation). For the GpG-ODN group, *p < 0.05 (vs. PBS); #p < 0.05 (vs. CpG-ODN). Levels of IgG1 (B) or IgG2a (C) in supernatants from unstimulated, purified B cells (Experiment 1) were assayed by ELISA after 48h in culture. For (B) and (C), *p < 0.05 (CpG-ODN vs. PBS); **p < 0.05 (GpG-ODN vs. PBS).