CD33 and myeloid neoplasm: When CD33 and CLL-1 CAR T cells were co-cultured with different myeloid tumor cells such as U937, THP-1 and HL60, all of them induced CAR down-regulation, however, THP-1 and MOLM-13 cell lines did not induce CAR down-regulation when they were co-cultured with CD123 CAR T cells.