Abstract
Myeloid derived suppressor cells (MDSCa) are a heterogeneous population of cells that promote an immunosuppressive environment in tumor-bearing hosts. Recently, B7-H1 signaling has been reported to be critical for the maintainancer of regulatory T cells (Tregs), another immunosuppressive cell population. Here, we discuss the immunosuppressive function of B7-H1 on MDSCs, and the functional crosstalk between Tregs and MDSCs.