Soluble β-glucan augments antitumor monoclonal antibody-elicited therapeutic efficacy. (A) Groups of WT mice were implanted subcutaneously with RMA-MUC1, after 7 days, to allow tumor formation, were treated with different regimens. Both tumor progression and tumor-free survival were monitored. (B) Dectin-1^−/− or (C) C3^−/− mice were implanted with RMA-MUC1 tumor cells. After tumors were formed, mice were subject to different treatment as indicated. Tumor diameter was recorded at the indicated time. (D) Neutrophils were marginated from WT and CD11b^−/− mice treated with soluble PGG β-glucan for 1 week. iC3b-opsonized tumor cells and un-opsonized tumor cells were labeled with a different intensity of CFSE and mixed at a 1:1 ratio and incubated with neutrophils. Percent of cytotoxicity is shown. (E) WT mice treated with soluble PGG β-glucan in combination with antitumor mAbs were preinjected with anti–Gr-1 monoclonal antibody to deplete neutrophils or isotype the control monoclonal antibody. Tumor diameter and tumor-free survival were monitored.