Mice treated with early anti–IL-17 antibody have an increased percentage of Tregs in the BM and decreased IFN-γ levels in the plasma at day 10. CByB6F1 mice were irradiated (5 Gy TBI) and injected with 5 × 10⁶ B6 LN cells. Early anti-IL-17 neutralization consisted of 100-μg intraperitoneal injections on alternating days from 3 days before the LN injection to 3 days after (n = 5). Controls consisted of LN-injected mice (n = 3) and mice only irradiated (n = 2). CD4⁺ and CD8⁺ BM cells were assessed at day 10 for IL-17 and IFN-γ expression. CD4⁺FOXP3⁺ cells were also measured. Cytokine levels in the plasma were measured by enzyme-linked immunosorbent assay. White bars represent the group of mice who did not receive anti–IL-17 neutralization; gray bars, mice that did receive anti–IL-17 neutralization; and black bars, TBI-only controls. (A) Absolute numbers of IL-17⁺ and IFN-γ⁺ cells in CD4⁺ (left panel) and CD8⁺ (right panel) subsets at day 10, according to the anti–IL-17 neutralization. Experiments are represented as mean ± SD. (B) Frequencies of CD4⁺ FOXP3⁺ cells. Experiments are represented as mean ± SD. (C) Cytokine levels in the plasma measured by enzyme-linked immunosorbent assay at day 10. Experiments are represented as mean ± SD.