Comparative heat sensitivity of murine and human hemopoietic progenitors and clonogenic leukemia cells

The aim of this study was to compare the thermal sensitivity of normal murine and human hemopoietic progenitors to that of leukemic murine and human clonogenic cells in order to assess the clinical relevance of experimental data. Colony forming units-granulocyte-macrophage (CFU-GM) from normal human bone marrow and from bone marrow of patients with acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), and Hodgkin's disease in complete remission proved to be less sensitive to 42.5 degrees C in vitro hyperthermia (D0: 93.9 min) than murine bone marrow CFU-GM (D0: 49.6 min). Leukemic colony forming cells (CFU-L) from HL-60 suspension culture--when compared to human CFU-GM--showed significantly increased thermal sensitivity (D0: 22.8 min). While the thermal sensitivity of CFU-L from a murine leukemia cell line (WEHI 3-B) was not statistically significant when compared to that of CFU-L from HL-60 (D0 values 17.0 versus 22.8 min), the vertical difference between the parallel regression lines suggested an approximately three-fold greater survival for human CFU-L. Although carefully controlled hyperthermia is an easy purging technique, the relevance of murine data to human clinical practice must be considered critically.