Figure 1: Lymph nodes contain resident CD4⁺ T cells.

(a) Frequency of D-Red⁺ among CD4⁺ T cells in cervical LNs (cLN) and mLN immediately (upper panel) and 7 days (lower panel) after photoconversion of mLN (representative of three independent experiments). (b) CD62L expression on all CD4⁺ (grey-filled histogram) and D-Red⁺CD4⁺ T cells (red line) in cLN (left) and mLN (right) 7 days after photoconversion of mLN (representative of three independent experiments, n=9 mice). (c) Frequency of D-Red⁺ among all CD4⁺ (left), CD4⁺CD62L^hi (middle) and CD4⁺CD62L^lo (right) T cells 7 days after photoconversion of mLN (n=5 mice in two independent experiments, mean±s.d., one-way analysis of variance (ANOVA), Tukey’s post test, **P<0.01; ***P<0.001; not significant (NS)). (d) Frequency of CD62L^hi and CD62L^lo cells among CD4⁺ (left) or CD4⁺D-Red⁺ (right) T cells 7 days after photoconversion of mLN from data in c (mean±s.d.). (e) Frequency of D-Red⁺ among CD4⁺CD62L^lo T cells in cLN, iLN_conv (photoconverted iLN), iLN_ctrl (non-photoconverted iLN) and PPs 7 days after photoconversion of iLN (n=4 mice in two independent experiments, mean±s.d., one-way ANOVA, Tukey’s post test, ***P<0.001; not significant (NS)). (f) Frequency of CD62L^lo among all CD4⁺ T cells in mLN and PP of WT C57BL6/N mice at different ages (n=5–8 mice per time-point in four independent experiments, unpaired Student’s t-test, ***P<0.001).