Heat production rate in polymorphonuclear granulocytes from patients with acute myelogenous leukaemia and healthy individuals

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.

Inhibition of platelet aggregation by myeloid leukaemic cells demonstrated in vitro

The effect of myeloid leukaemic cells, cells of the promyelocytic cell line HL-60 and normal polymorphonuclear granulocytes (PMN), enclosed in dialysis tubes, on the aggregation of allogeneic normal platelets after induction with arachidonic acid (AA) and with adenosine diphosphate (ADP) was investigated in vitro. Inhibition of aggregation was seen after preincubation of the platelets with leukaemic blood or bone marrow cells from 7/14 patients belonging to various FAB groups and with HL-60 cells, but not with normal PMN (14/14 cases). A dose-dependent inhibition was seen after lysis of some leukaemic cells with anti-human rabbit antiserum and active complement. Lysis of normal PMN inhibited platelet aggregation slightly and inconstantly and only at higher cell concentrations. Platelet inhibitory activity was not related to a higher rate of metabolism of the leukaemic cells which inhibited platelet aggregation since they did not differ from the cells not inhibiting aggregation with respect to heat production. Neither was a non-specifically increased cell membrane permeability the cause of the release of platelet inhibitory factor(s) since the release of 51Cr-labelled leukaemic cells was not related to the inhibition of platelet aggregation.

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.

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

Functional activity of granulocytes from healthy individuals and from patients with acute leukemia in remission was studied. The increase of heat production rate (metabolic activity) after stimulation of the blood cells with in vitro formed immune complexes was measured by microcalorimeters of heat conduction type. It was demonstrated that increased heat production rate after exposure to immune complexes was significantly lower (p less than 0.0005) in 9 patients with acute leukemia with a remission duration of less than 6 months than in 25 healthy volunteers.