Decreased responsiveness to immune complexes of granulocytes from patients with acute leukemia in remission demonstrated by microcalorimetry

Direct microcalorimetry as a technique in cell cultures

In vitro studies of energy metabolism in isolated cells contribute to improved knowledge of human energy metabolism under normal and pathological conditions. In every cellular system energy is taken up, metabolized and finally transformed into heat, which is dissipated into the environment. Thus, energy turnover of isolated cells can be assessed by microcalorimetric determination of their heat production. Microcalorimeters of the thermopile heat conduction type facilitate direct physical determination of thermogenesis with a sensitivity of 0.2 microW; 10(4)-10(5) cells being sufficient for one measurement. Peltier elements are sandwiched between the sample and a precisely thermostated heat sink, creating a detectable voltage proportional to the heat production. For adequate interpretation of the results, simultaneous biochemical investigations of relevant metabolic pathways are required. Up to now, numerous studies with blood cells, skeletal and heart muscle cells, hepatocytes, endothelial cells, fibroblasts and adipocytes have been performed in relation to various diseases and under the influence of certain hormones and pharmacological agents.

Differentiation of myeloid leukemic cells in vitro demonstrated by microcalorimetry: stimulation of leukemic and remission cells by IgG-binding Fc receptors

Interaction of immunoglobulin G (IgG)-coated latex particles with Fc receptors on myeloid leukemic blood cells and on polymorphonuclear granulocytes (PMN) from remission patients and healthy blood donors was investigated using microcalorimetry. The induced heat production by leukemic cells from 13 patients with the M2, M4 and M5 FAB groups (French-American-British classification) of acute myeloid leukemia (AML) was significantly higher than that of leukemic cells from 7 patients with the M1 FAB group (p less than 0.005) and mononuclear blood cells from 10 healthy individuals (p less than 0.005). The values were similar for PMN from 10 remission patients and 10 healthy blood donors. After incubation of M1 cells in vitro for 24-30 h at 37 degrees C the heat production induced by IgG-coated latex particles by the cells increased significantly, indicating the appearance of Fc receptors for IgG. In addition, the heat production by unstimulated M2, M4 and M5 cells was significantly higher than that by unstimulated M1 cells (p less than 0.005) and normal mononuclear cells (p less than 0.0005). The heat production by unstimulated PMN suspended in tissue culture medium was similar in remission patients and healthy blood donors.