This augmentation of cytokine secretion presented only in chips where CAR T cell interacted with CD19+ leukemia blasts but not in those where Mock T cell interacted with CD19+ leukemia blasts or CAR T cell with CD19 knockout (CD19−) ones (Extended Data Fig. 6c), confirming the specificity and efficacy of anti-CD19 CAR T cell therapy. The gene discussed is CD19; the disease is leukemia.