CD19 and breast cancer: We analyzed the influence of sPD-L1 on the survival of PD-L1hi MDA-MB231 in a T-/B-cell/tumor coculture system with CD19+ B cells activated by LPS or sPD-L1 (Figure 6A) and further investigated PD-L1 signal blockade for immunotherapy in PD-L1hi MDA-MB231, a breast cancer cell line of TNBC (Figure 6C).