Studies on sensitivity of human GM-CFU and L-CFU to hyperthermic killing in vitro

The thermal sensitivity of normal myeloid and leukaemic cells was compared using morphology, cytochemistry and cultures of granulocyte-macrophage and leukaemic progenitor cells (GM-CFU and L-CFU). We have clearly demonstrated that blast cells from eight cases of acute nonlymphoblastic leukaemia (ANLL) showed greater morphological deterioration and loss of cytoplasmic enzymes with continuous heating at temperatures of 40-43 degrees C than normal marrow mononuclear cells obtained from ten controls. Survival of L-CFU also decreased exponentially with rising temperature whereas GM-CFU were not markedly affected, even at a temperature of 43 degrees C for 30 min. These results suggest that human L-CFU are more sensitive to hyperthermic killing than normal human GM-CFU and that hyperthermia might selectively purge residual leukaemic cells in vitro. Hyperthermia may have a role in clinical autologous bone marrow transplantation (ABMT) for acute leukaemia.