CD4 and lymphoma: In a mouse model of aggressive lymphoma, where tumor cells rely less on the TME for survival, the co-injection of MSCs with tumor cells induced a marked increase of immune cells including CD4+ T cells, CD11b+ cells, CD4+Foxp3+ TRegs, and CD11b+Ly6C+Ly6G− MDSCs (256), demonstrating that the CAF secretome can modulate the recruitment and/or polarization of different immune subpopulations.