Fig 7.

Chemokine receptor expression is not associated with large differences in B helper function. (A, top) Representative overlay histogram plots of PD-1 expression among ICOS⁺ CD4⁺ T cells (gray line, X5⁻/X4⁻; red line, X5⁻/X4⁺; blue line, X5⁺/X4⁻; black line, X5⁺/X4⁺). (Bottom) Colored dot plots for the expression of Bcl-6 and CXCR4 among ICOS⁺ CXCR5⁺ (black) and ICOS⁺ CXCR5⁻ (green) cells. CXCR4⁺ cells (i.e., largely ICOS⁺ X5⁺/X4⁺) are enriched for Bcl-6 expression in both frequency and intensity. Bar graphs indicate mean frequencies ± SD of expression of the indicated surface marker within the given ICOS⁺ population. Data were pooled from two experiments analyzing individual mice (n = 4 each). (B) Gene expression analysis of FACS-purified MedLN CD4 T cell subsets isolated from influenza virus A/Mem71-infected mice at day 10 (n = 4). Shown are transcript levels relative to GAPDH expression levels. Data are representative of two replicate experiments (one with BALB/c mice and one with C57BL/6 mice). (C, top) Shown are 5% contour plots of CD4 T cells pre- and post-FACS purification. T cells were cocultured with MACS-enriched CFSE-labeled B cells from lymph nodes of influenza virus-immunized mice, as outlined in the legend of Fig. 1. Cells were cultured in triplicate, and mean frequencies ± SD of proliferating CFSE^lo B cells (left) and relative antibody concentrations in supernatants (right), as assessed by ELISA, are displayed. RU, relative units. Results are from one of two experiments that yielded comparable results.