FIGURE 4.

(A) Compared with naïve mice, peripheral blood of 4T1 tumor-bearing mice contains elevated proportions of IL10 and FoxP3–expressing CD4⁺ T cells. Numbers represent % of IL10⁺ and FoxP3⁺ within (gated) CD4⁺ cells, as compared with isotype control IgG. (B) IL10 KO mice were i.v injected with PBS or adoptively transferred with 5×10⁶ Tregs (CD25⁺CD4⁺) purified from naïve IL10 KO or WT BALB/C mice one day before and 5 days after s.c. challenge with 4T1.2 cancer cells (day 0). At day 28, tumor growth (C) and metastasis in the lungs (D) were compared with ones in control BALB/c mice (WT mice) challenged with 4T1.2 cells in a side-by-side experiment. Y-axis shows weight (g) of primary tumor (C) and number of metastatic foci in the lungs (D) ± SEM of five mice per group experiment. All results were reproduced at least twice. *P<0.05 is for comparisons between naïve and tumor-bearing mice (A) and groups injected with WT and IL10 KO Tregs (C, D).