FIGURE 5.

EGR2/3-deficient CD4 T cells failed to induce GC formation in Rag2^−/− mice. Naive CD4 and B cells were isolated from wild type and CD2-Egr2^−/−Egr3^−/− mice. Wild type CD4 cells were mixed with EGR2/3-deficient B cells (WT-CD4/K2-3-B220), and wild type B cells were combined with EGR2/3-deficient CD4 cells (K2-3-CD4/WT-B220) at equal cell numbers of B and CD4 cells. Wild type CD4 cells together with wild type B cells (WT-CD4/WT-B220) served as a control. These mixtures of cells were then adoptively transferred into Rag2^−/− mice. 40 days after transfer, recipient mice were infected intranasally with 2 × 10⁵ pfu of vaccinia virus and analyzed 14 days after infection. A, CD4 and B220 cells from spleen and lymph nodes were gated for analysis of CD4⁺CXCR5⁺PD1⁺ Tfh cells (left) and B220⁺GL7⁺ GC B cells (right). B, CXCR5⁺PD1⁺ and B220⁺GL7⁺ populations were quantified as a percentage of total CD4⁺ or B220⁺ cells. C, splenic tissue sections were stained with anti-B220 (blue), PNA (red), and anti-CD3 (green). In B, each symbol represents an individual mouse from two independent experiments (indicated by different colored symbols); error bars, S.E. on either side of the mean. *, p < 0.01; N.S., not significant (Mann-Whitney two-tailed test). Data are representative of two independent experiments with three mice in each group.