The function of differentiated iNK cells was investigated by in vitro co‐culture assays with various lymphoma cells, including K562 (CD19‒, CML), CD19‐K562 (CD19+), Nalm‐6 (CD19+, ALL), and Raji (CD19+, Burkitt's). Here, CD19 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.