IgG1⁺ precursors are required for constitution of the memory IgE response.

<p>(A) GC B cells (B220⁺CD38^loGL-7⁺; left plots) and intracellular IgE⁺ or IgG1⁺ expression on gated GC B cells (right plots) in mesenteric LN samples from day 14 <i>N</i>. <i>brasiliensis</i>-infected IgE^ki/ki and wild-type C57BL/6 mice. (B) PCs (B220⁻CD138⁺; left plots) were gated from blasts (FSC^hiSSC^hi), and percentage of intracellular IgE⁺ and IgG1⁺ PCs is shown in the right plots. (C) Serum IgE in IgE^ki/ki and C57BL/6 mice after first and secondary <i>N</i>. <i>brasiliensis</i> infection. (D) Ratio of IgE^b to IgE^a in IgE^ki(a)/wt(b) or IgE^wt(a)/wt(b) mice after first and secondary <i>N</i>. <i>brasiliensis</i> infection. (E) 1.5 x 10⁵ sorted B220⁺IgM⁻IgD⁻IgE⁻, B220⁺IgM⁻IgD⁻IgG1⁻, B220⁺IgG1⁺ B cells or IgG1⁻CD138⁺ PCs gated as indicated in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002290#pbio.1002290.s008" target="_blank">S7 Fig</a> from IgH^a mice on d13 after secondary <i>N</i>. <i>brasiliensis</i> infection were transferred into nonirradiated IgH^b mice. Recipient mice were infected with <i>N</i>. <i>brasiliensis</i> and IgE^a was determined in the serum on day 12 after infection. Data show the mean + SEM from four independent experiments and at least seven mice (A and B), two experiments with eight mice total per group (C), two experiment with 2–7 mice (E). *<i>p</i> < 0.05, ***<i>p</i> < 0.001 by Student’s <i>t</i> test. n. d. = not detectable.