CD19 and leukemia: This augmentation of cytokine secretion presented only in chips where CAR T cell interacted with CD19+ leukaemia blasts but not in those where Mock T cell interacted with CD19+ leukaemia blasts or CAR T cell with CD19− ones (Supplementary Fig. 6c), which together confirm the specificity and efficacy of anti-CD19 CAR T cell therapy.