The sensitivity to hyperthermia of human granulocyte/macrophage progenitor cells (CFU-GM) derived from blood or marrow of normal subjects and patients with chronic granulocytic leukaemia.

To compare the relative heat sensitivities of human normal and neoplastic cells of the same tissue type, a study was carried out of the relative sensitivities to heat of granulocyte/macrophage progenitor cells (CFU-GM) derived from the peripheral blood and bone marrow of normal subjects and patients with chronic granulocytic leukaemia (CGL). Nucleated haemopoietic cells were incubated at temperatures in the range 41.5 degrees C to 44.0 degrees C for various periods before culture in agar. The results of these experiments showed that CFU-GM from normal blood were consistently less sensitive to damage by heat than normal marrow CFU-GM. There was no comparable difference in the relative heat sensitivities of CFU-GM from blood and marrow of patients with CGL and no significant difference between the heat sensitivities of CFU-GM derived from marrow from normal individuals and patients with CGL. The observed difference in heat sensitivity of CFU-GM from normal blood and marrow accords with other data suggesting that the two progenitor cell compartments are distinct: the blood CFU-GM may represent a more primitive population of committed progenitor cells. In CGL, CFU-GM in the blood may much more closely resemble those in the marrow. The data provide no support for the hypothesis that malignant cells differ intrinsically from their normal counterparts in respect of sensitivity to damage by hyperthermia.