Fig. 2. Vβ5⁺ Treg cells are suppressive but not required for regulating anti-viral immunity.

Foxp3-GFP.KI mice were infected with 200 f.f.u. LCMV WE (acute), 10⁶ f.f.u. LCMV clone 13 (chronic), or were left naïve. a–c Mean fluorescence intensity (MFI) of Foxp3-GFP expression and frequencies of TIGIT⁺, PD-1⁺, Lag-3⁺, Tim3⁺, CD39⁺, and CD73⁺ cells among the indicated CD4⁺Foxp3⁺ subsets were determined on day 14 post infection using flow cytometry (n = 5). d Foxp3-GFP.KI mice were infected with 200 f.f.u. LCMV WE and flow sorted Foxp3⁺CXCR3⁺Nrp1⁻Vβ5⁺ (filled), Foxp3⁺CXCR3⁺Nrp1⁻Vβ8⁺ (open) or Foxp3⁺CXCR3⁺Nrp1⁺Vβ5⁺ (grey) Treg cells were titrated onto CD4⁺Foxp3⁻ effector T cells stimulated with anti-CD3 in the presence of irradiated APCs. Proliferation (left, n = 3 technical repeats) determined by [³H]-thymidine incorporation and IFN-γ secretion into supernatants (right, Treg:Tcon = 1:4) determined by cytometric bead array were measured after 72 h (mean ± SD, n = 4–6, pooled data of three independent experiments). e Scheme for TCR-defined CD4 T cell reconstitution. f, g Mice generated as outlined in e were infected with 10⁶ f.f.u. LCMV clone 13 (n = 2–7). f On day 17 splenocytes were restimulated with gp61 + gp33 LCMV peptides for 4 h and analyzed for IFN-γ production by flow cytometry. g Viral titers of the indicated organs were determined on day 17 post infection. DEREG mice depleted of Treg cells by diphtheria toxin treatment (day 4, 6, 8, 10, 12; n = 3) and analyzed for viral titers on day 14 were included as controls. Data are shown as mean ± SD; plots display one representative of >3 independent experiments. For statistics, Mann–Whitney U was used.