CD4 and neoplasm: Tumor-infiltrating LY6G MDSCs from orthotopic liver tumors treated with sorafenib significantly induced CD4+T cells expressing IL-10 and TGF-β and down-regulated the cytotoxic activity of CD8 T cells. IL-6 protects LY6G MDSC against sorafenib induced cell death in vitro. The combination of anti-LY6G antibody or anti-IL-6 antibody and sorafenib significantly reduced the cell proportion of LY6G MDSCs in orthotopic liver tumors, enhanced the proliferation of T cells, and synergically improved the therapeutic effect of sorafenib.