Figure 4. Mixed chimeras reveal a cell extrinsic requirement for Foxp3 in Th17 differentiation.

A) Schematic of the experiment designed to determine whether Foxp3 expression is a cell extrinsic or intrinsic requirement for Th17 differentiation.

B) 10⁷ total bone marrow cells from B6.Foxp3^DTR CD45.2 mice only (DT control), or mixed 1:1 with bone marrow cells from B6.Foxp3^WT CD45.1 mice, were transferred retro-orbitally into Rag1^−/− recipients that had received 300 rads irradiation 5-6 hours prior. Following 6 weeks for hematopoietic cell reconstitution, mice were inoculated with ETBF or sham on day 0, and either 150 μl purified sterile H₂O or 50 ng/g DT was administered ip on days −2, −1, 1, 3, & 5. Colonic LPLs from 1-2 mice were harvested on day 7 following ETBF or Sham inoculation. Cells were stimulated ex vivo followed by ICS. Dot plots show viable CD3⁺ CD4⁺ LPLs and are representative of 2 experiments.

C) Colon LPLs from 1 B6.Foxp3^DTR mouse per group were harvested on day 7 following inoculation with ETBF or sham on day 0. For no depletion and early depletion, purified sterile H₂O or DT, respectively, was administered ip on days −2, −1, 1, 3, & 5. For late depletion, DT was administered ip on days 1, 3, & 5. Cells were stimulated ex vivo, followed by ICS. Plots show viable CD3⁺ CD4⁺ Foxp3- LPLs and are representative of 2 mice per group.