CD33 and acute myeloid leukemia: After CD33-CAR-NK cell infusions, the proportion of leukemic cells in the patients’ bone marrow significantly decreased from 40% to 26%; the proportion of CD33+ cells in bone marrow reduced from 48.82% to 32.56%, and the proportion of CD33+CD34+ cells in bone marrow reduced from 40.59% to 27.26% respectively in a 53 years old male patient with AML-M1.