CD19 and neoplasm: Previous studies have demonstrated that the TILs in breast cancer tissue are mainly composed of cytotoxic T (CD8+) cells, helper T (CD4+) cells, B (CD19+) cells and natural killer (NK) cells (4, 5), and the subtypes of TILs can affect the tumor cells and immune cells in multiple ways, consequently contributing to either an anti-tumor or pro-tumor effect (6–8).