Adoptive transfer of PLCγ2^−/− MDSCs enhances tumor growth in WT mice. (A) WT mice s.c. inoculated with LLC cells were adoptively transferred on days 3 and 6 with 3 × 10⁶ WT or PLCγ2^−/− MDSCs from LLC tumor–bearing mice. Tumor growth was followed for 14 d, and the percentage of Gr-1⁺CD11b⁺ MDSCs isolated from spleens was determined by FACS. Mean ± SD (n = 5) are shown. Data are reported from one of two similar experiments. **, P < 0.01; ***, P < 0.001. (B) 3 × 10⁶ WT or PLCγ2^−/− MDSCs were isolated from the spleen of tumor-bearing CD45.2⁺ mice and inoculated i.v. into CD45.1⁺ WT mice on days 3 and 6 after LLC tumor challenge. The tumor growth in CD45.1⁺ WT recipients was monitored for 14 d, and the percentage of endogenous CD45.1⁺ Gr-1⁺CD11b⁺ MDSCs in spleen was determined by FACS. Mean ± SD (n = 5) are shown. Data are reported from one of two similar independent experiments. *, P < 0.05; **, P < 0.01.