Phagocytosis of latex beads by a human monocytic Mono Mac 6 cell line and effects of low-frequency electromagnetic field interaction.

Some studies have shown that electromagnetic fields (EMFs) may impact immune response cells and their functions. The first stage of the defense from pathogens is innate immunity encompassing phagocytosis and phagocytosis-related intracellular effects. Our work aimed to determine the influence of a low-frequency electromagnetic field (7 Hz, 30 mTrms) on the phagocytosis process of latex beads (LBs), the production of reactive oxygen species (ROS), and viability changes in a human monocytic Mono Mac 6 (MM6) cell line as an experimental model of the phagocytosing cells in in vitro cell culture conditions. For these purposes, cells were firstly activated with infectious agents such as lipopolysaccharide (LPS), Staphylococcal enterotoxin B (SEB), or the proliferatory agent phytohaemagglutinin (PHA), and then a phagocytosis test was performed. Cell viability and range of phagocytosis of latex beads by MM6 cells were measured by flow cytometry, and the level of ROS was evaluated with the use of a cytochrome C reduction test. The obtained results revealed that applied EMF exposure mainly increased the necrosis parameter of cell death when they were pre-stimulated with SEB as an infectious factor and subsequently phagocytosed LBs (P=0.001). Prestimulation with other agents like LPS or PHA preceding phagocytosis resulted in no statistically significant changes in cell death parameters. The level of ROS depended on the used stimulatory agent, phagocytosis, and/or EMF exposure. The obtained effects for EMF exposure indicated only a slight decrease in the ROS level for cells phagocytosing latex beads and being treated with SEB or PHA, while the opposite effect was observed for LPS pre-stimulated cells (data not statistically significant). The results concerning the viability of phagocytosing cells, the effectiveness of the phagocytosis process, and the level of radical forms might result from applied EMF parameters like signal waveform, frequency, flux density, and especially single EMF exposure.

Low-frequency electromagnetic field influences human oral mucosa keratinocyte viability in response to lipopolysaccharide or minocycline treatment in cell culture conditions.

The aim of the current study was to investigate the influence of low-frequency electromagnetic field (LF-EMF) exposure on viability parameters of oral mucosa keratinocytes cultured in in vitro conditions. The effect of LF-EMF stimulation on cell viability was also specified in the simultaneous presence of lipopolysaccharide (LPS) infectious agent or minocycline (Mino) anti-inflammatory agent. Viability parameters such as early-, late apoptosis and necrosis of keratinocytes were analysed by the flow cytometry method (FCM). The exposure of human oral keratinocyte cell cultures to LF-EMF acting alone or combined with LPS/minocycline agents caused changes in the percentage of cells that undergo programmed or incidental cell death. The overall obtained results are compiled in a graphical form presented in Fig. 1.

Changes in U937 cell viability induced by stress factors - possible role of calmodulin.

Current studies were aimed to elucidate influence of magnetic field (MF) stimulation on cell viability and its effect on expression of calmodulin (CaM) and Hsp70 protein which plays a role of cell stress indicator and is a Ca2+-dependent CaM-binding protein. For the experimental model we have chosen U937 cell line exposed to chemical- and/or physical stress factors. Puromycin (PMC) was used as a chemical apoptosis inducer. Alternating (AC) (6.5rms mT, 35 Hz) magnetic field combined with 6 mT static (DC) component, or pulsed electromagnetic field (45 ± 5)mT, 50 Hz (PEMF) acted as physical stressors. Cell viability was assessed by flow cytometry, and the Western blot analysis was carried out for CaM and Hsp70 levels in cytosolic extracts of U937 cells. Cell viability in samples exposed to MF alone did not differ from sham sample, for both types of MF exposure systems. Simultaneous action of MF and PMC influenced cell viability in type of MF stimulation-dependent manner. In contrast to PEMF + PMC stimulated samples, combination of ACDCMF with PMC enhanced cell death compared to PMC control. The observed changes in cell viability were correlated with changes in level of CaM and Hsp70 proteins. Immunoblots have shown, that cytosolic content of both CaM and Hsp70 proteins was enhanced in PMC-treated sample, and further elevated for ACDCMF + PMC. For PEMF + PMC stimulated samples, level of CaM was reduced compared to PMC-treated sample. The results suggest that the changes in expression of CaM and CaM-dependent proteins might modulate effectiveness of cell death under stimulation with MF and/or cytotoxic agents.