Amygdalin (Laetrile): effect on clonogenic cells from human myeloid leukemia cell lines and normal human marrow.

The effect of amygdalin on human acute myelogenous leukemia cells and normal bone marrow granulocyte-monocyte precursors was studied in vitro using soft-gel culture. A pharmaceutical and a clinical source of amygdalin were tested and beta-glucosidase was added to selected cultures to promote the hydrolysis of amygdalin. Acute myelogenous leukemia cells were obtained from two human cell lines designated KG-1 and HL-60. A 50% inhibition of colony formation by both normal and leukemic cells was observed at an amygdalin concentration of 3.5 mg/ml using both drug sources. We found the colony-forming cells from the leukemic cell lines and normal marrow to be relatively resistant to amygdalin and its metabolites in vitro, and there was no selective kill of clonogenic cells from the human leukemia cell lines as compared to normal bone marrow.