Anti mouse cd11b beads

The MDSCs isolated from the spleen and tumor tissue of tumor-bearing mice were isolated using a mouse MDSC isolation kit (Miltenyi Biotec, Auburn, CA, USA) following the manufacturer’s protocol. To isolate MDSCs from the spleen, the spleen of tumor-bearing mice was removed aseptically and then minced to obtain single-cell suspensions. The obtained cells were stained with anti-mouse-CD11b-beads (Miltenyi Biotec, Auburn, CA, USA) for 30 min and washed with PBS twice. Then, cells were subjected to isolation with a column. To isolate MDSCs from the tumor tissues of tumor-bearing mice, tumor tissues were cut into small pieces (1–2 mm³) and digested with collagenase II (Sigma-Aldrich, St. Louis, MO, USA) at 37°C for 2 h on a rotating platform to obtain single-cell suspensions. The obtained cells were stained with anti-mouse-CD11b-beads (Miltenyi Biotec, Auburn, CA, USA) for 30 min and washed with PBS twice. Then, cells were subjected to isolation with a column. The purity of MDSCs isolated from spleen and tumor tissues was greater than 90 and 80%, respectively.

MDSCs were isolated from erythrocyte‐depleted splenocytes using antimouse CD11b beads (Miltenyi Biotech, Bergisch Gladbach, Germany) following the manufacturer's instructions. In some experiments, MDSCs were sorted by FACSAria (BD Biosciences). The purity of MDSCs (CD11b⁺Gr‐1⁺) was typically >90%. Splenic CD8⁺ T cells were enriched using anti‐CD8 beads (Miltenyi Biotech). The purity of CD8⁺ cells was typically >95%.