Figure 3.

Increased liver immune-suppressive cells in the liver of tumor-bearing (TB) mice. Sex- and age-matched wild-type (WT) mice were either untreated or inoculated with 1 × 10⁶ B16 cells. Fifteen days postinoculation, liver mononuclear cells were prepared and analyzed through flow cytometry (n = 6). (A) The percentage and absolute number of CD11b⁺Gr1⁺ myeloid-derived suppressor cells (MDSCs) (mean ± SEM) are shown. (B) One representative FACS staining in panel (A) is shown. (C) The percentage and absolute number of CD4⁺Foxp3⁺ T regulatory cells (Tregs) (mean ± SEM) are shown. (D) One representative FACS staining in panel (C) is shown. (E) Depletion of MDSC, but not Tregs, restored concanavalin A (Con A)-induced hepatitis in TB mice. TB mice were either untreated or intraperitoneally injected with 0.2 mg anti-Gr1 (clone RB68C5) or anti-CD25 (clone PC-61.5.3) prior to Con A treatment as described in Section “Materials and Methods.” Serum samples collected at 12 h post-Con A treatment were used for alanine aminotransferase (ALT) detection, and results from one typical experiment are shown (mean ± SEM, n = 7). (F) Adoptive transfer of MDSCs, but not Tregs, from TB mice protected WT mice against Con A-induced hepatitis. Sex- and age-matched WT mice were either untreated or adoptively transferred with 5 × 10⁵ CD11b⁺Gr1⁺ cells or CD4⁺CD25⁺ Treg cells from TB mice via intravenous injection prior to Con A injection. Serum samples collected at 12 h post-Con A treatment were used for analyzing ALT levels. Results from one representative experiment are shown (mean ± SEM, n = 5). Data represent at least three independent experiments with similar results.