Figure 1 Immunoglobulin response to CpG oligonucleotides. B cells from T-bet-deficient (squares) or T-bet-sufficient (circles) C57BL/6 mice were incubated in culture for 10 d in the presence of antibody to CD40 and recombinant murine IL-4, in the presence (CpG) or absence (None) of stimulatory CpG oligonucleotides. Secreted IgE or IgG2a titers were determined by enzyme-linked immunosorbent assay. Results for IgG1 (data not shown) were analogous to those of IgE, presented here.*, titers below the limit of the assay (2.5 ng/ml). Each data point represents B cells isolated from one individual mouse; data are representative of three experiments, reflecting five to seven mice per genotype.