The use of [[ https://bcc.creative-bioarray.com/immune-cell-identification-and-selection.htm | chimeric antigen receptor ]] (CAR) T cells is gaining traction as one of the most promising advances in cancer immunotherapy, which is also the first approved cell-based immunotherapy by The US Food and Drug Administration. Meanwhile, researches on CAR-NK cells and TCR-engineered T cells became a promising breakthrough in recent years, because of their great potential in immunotherapy. In these great technologies, identification and selection of immune cells is the first and essential step in immune cell engineering technology.