Multipotency of CD11bhighGr-1+ immature myeloid cells accumulating in oral squamous cell carcinoma-bearing mice.

We demonstrated the accumulation of CD11b(high)Gr-1(+) cells in a murine model of squamous cell carcinoma (SCC). Inoculation of NR-S1K cells derived from oral SCC induced a rapid and clear accumulation of CD11b(high)Gr-1(+) cells in secondary lymphoid organs as well as in peripheral blood. Phenotypic and morphological analyses revealed that these CD11b(high)Gr-1(+) cells were not lymphoid lineage cells, mature dendritic cells, macrophages, or granulocytes. Although the freshly isolated CD11b(high) cells lacked antigen-presenting capacity, they acquired a potent antigen-presenting capacity that included the induction of MHC class II after culture with GM-CSF and IL-4 in vitro. These results suggest that CD11b(high) cells that accumulate in tumor-bearing hosts are immature myeloid cells, but have considerable potential to differentiate into potent antigen-presenting cells under appropriate culture conditions. The use of in vitro differentiated CD11b(high) cells may be a potential strategy for obtaining patient-matched dendritic cells for tumor immunotherapy.