CD19 and neoplasm: Using a syngeneic murine model of lung cancer with intravenous implant LLCs, we first studied the kinetics of infiltration of CD19+CD1dhiCD5+IL-10+ Bregs which significantly increased in a time-dependent manner (Figure 1A). We and others have previously reported that immunosuppressive MDSCs are important drivers of tumor growth in this tumor model (41, 45).