Figure 5. CD4⁺Foxp3⁺ T cells have a regulatory phenotype.

(A) Skin suction blisters were induced on day 7 following VZV injection. Blister cells and PBMC were stained in parallel and analysed by multi parameter flow cytometry. First, live cells were gated on either CD4⁺Foxp3⁺ or CD4⁺Foxp3⁻ (left dotplot). Representative expression of CD25, CD127 and CD39 is shown in the histograms (n=6). (B) Day 7 blister cells were stimulated o/n with VZV lysate and IFN-γ production was measured by intracellular cytokine staining. CD4⁺ population was gated based on Foxp3 and CD127 expression and the subsets (as indicated) compared in terms of cytokine production. Representative dot plots of n= 5 are shown. Quadrants were set on the isotype control and unstimulated cells (not shown). (C) The proportion of Foxp3⁺CD4⁺ T cells in the skin inversely correlates with the clinical score (each symbol represents one individual, linear regression analysis p=0.007). Representative immunofluorescence staining from individuals with low or high clinical score are shown. The clinical score on day 3 following injection is plotted against the % of Foxp3 expressing CD4⁺ cells found in the skin at the peak of the cellular response (mean of 5 largest PVs counted for each individual).