Figure 4

CD4⁺ T cells CD45RA and CCR6 expression at the site of intradermal S. pnuemoniae challenge. Data were obtained by flow cytometry of blister fluid collected at 4 h and 48 h after intradermal inoculation 7.5 × 10⁵ CFUs of UV-killed TIGR4 S. pnuemoniae (6 donors) and in pre-challenge peripheral blood (2 to 4 donors). (A) reprentative flow cytometry plots of CCR6 and CD45RA expression. (B) Mean (SD) percentages of CD45RA⁻ (grey) and CD45RA⁺ (black) cells in the CD4⁺CD25⁺CD127^low populations analysed by two-way ANOVA and Tukey’s multiple comparisons test comparing 0 h blood samples with the 4 h and 48 h blister samples (*p < 0.05; **p < 0.01). (C) Mean (SD) percentages of CD4⁺ T cells expressing CCR6. Data were analysed using one-way ANOVA (p < 0.01) with Dunnett’s multiple comparisons test (*p < 0.05; **p < 0.01). (D) Mean (SD) expression of both CD45RA and CCR6 by the CD4⁺ T cell and CD4⁺CD25⁺CD127^low populations analysed by two-way ANOVA and Tukey’s multiple comparisons test comparing CCR6^+/−CD45RA^+/− expression in the 0 h blood samples wit the 4 h and 48 h blister samples (*p < 0.05; ***p < 0.001; ****p < 0.0001).