Changes in cell proliferation due to environmental non-ionizing radiation 1. ELF electromagnetic fields

We aimed to find out how the exposure of isolated lymphocytes to a pulsed magnetic field (MF) affected their in vitro proliferative response to mitogenic stimulation. Cells were exposed to MF of various intensities (0.3, 0.6, and 1.2 T) at a constant frequency of 30 Hz, for a period of 60, 180, and 330 s. Then, the proliferative response of splenocytes was induced by optimal concentrations of concanavalin A (Con A; mitogenic toward T cells), bacterial lipopolysaccharide (LPS; mitogenic toward B cells), or pokeweed mitogen (PWM; mitogenic toward both populations). We found that the exposure of lymphocytes to the MF profoundly inhibited their proliferative response to mitogens. The suppressive action of the MF on B and T cell proliferation was intensified when a cooperative response of those two lymphocyte populations was simultaneously induced by PWM. The inhibitory effect of MF depended on the exposure time and MF intensity. Prolonged exposure and/or a stronger intensity of the MF weakened its inhibitory influence on the response of lymphocyte to mitogenic stimulation. The data show that an exposure to MF may influence the activity of lymphocytes in their response to mitogenic stimuli.

Section: Discussionsupporting

confidence: 90%

Magnetic field inhibits isolated lymphocytes' proliferative response to mitogen stimulation

Román¹,

Zyss²,

Nalepa³

2005

“…Antonopoulos et al [1995] reported a stimulation of the cell cycle in dividing human lymphocytes that were exposed to 50 Hz, 5 mT fields. Kwee and Rasmark [1995] observed an increased proliferation rate in AMA cells that were exposed for 30 min to 50 Hz, 80 mT fields. Several other studies did not observe any alteration in the growth of cells in response to exposure to 50 or 60 Hz ELF-MF [e.g., Livingston et al, 1991].…”

Section: Discussionmentioning

confidence: 83%

Effect of coexposure to 50 Hz magnetic fields and an aneugen on human lymphocytes, determined by the cytokinesis block micronucleus assay

Verheyen

Pauwels

Verschaeve

et al. 2003

Interference of 50 Hz extremely low frequency magnetic fields (ELF-MF) with the known aneugen vinblastine (VBL) on micronucleus formation was tested with the in vitro cytokinesis block micronucleus assay in human lymphocyte cultures. Isolated lymphocyte cultures were prepared from 18 individuals. Three groups of quadruplicate cultures from six unrelated individuals were exposed to 50 Hz ELF-MF of background (bkg), 80 and 800 microT, respectively, during the complete incubation period (72 h). Twenty-four hours after culture initiation, one replicate culture from each individual within each ELF-MF group was exposed to 0, 5, 10, or 15 ng/ml VBL. The isolated lymphocyte cultures were scored for the presence of micronuclei, the nuclear division index (NDI), and apoptosis. As expected, increased VBL concentration resulted in an increased micronucleus and apoptosis frequency and in a decreased NDI. In the presence of VBL, there was a systematic tendency for increased micronucleus and apoptosis frequency in the ELF-MF exposed groups compared to the bkg group. In the absence of VBL, we observed no statistically significant effect of ELF-MF on micronucleus induction or apoptosis frequency, but the NDI was significantly higher in the 800 microT group compared to the other groups, suggesting an effect of ELF-MF on cell proliferation. An interaction between ELF-MF and VBL on NDI was observed. This interaction reflected the drastic decrease in NDI due to coexposure to VBL.

“…Although there have been numerous investigations of possible electromagnetic field effects on cell proliferation, the results have been largely inconsistent [Rosenthal and Obe, 1989;Livingston et al, 1991;Antonopoulos et al, 1995;Kwee and Rasmark, 1995;Cridland et al, 1996;Schimmelpfeng and Dertinger, 1997;Katsir et al, 1998;]. The experiments reported here were designed to investigate the cell proliferation response to residential or occupational magnetic field exposure levels by examining the number of cells growing under low fetal bovine serum culture conditions and by measuring the rate of DNA synthesis during initial cell proliferation.…”

Section: Introductionmentioning

confidence: 97%

No effect of extremely low‐frequency magnetic field observed on cell growth or initial response of cell proliferation in human cancer cell lines

Yoshizawa

Tsuchiya²,

Mizoe³

et al. 2002

An effect on the tumor promotion process, as represented by accelerated cell growth, has been indicated as one example of areas that demonstrate the possibility of biological effects of extremely-low frequency magnetic fields. We, therefore, exposed the five cell lines (HL-60, K-562, MCF-7, A-375, and H4) derived from human tumors to a magnetic field for 3 days to investigate the effects on cell growth. Prior to exposure or sham exposure, the cells were precultured for 2 days in low serum conditions. The number of growing cells was counted in a blind manner. To investigate the effect on the initial response of cell proliferation, two cell lines were synchronized in G1 phase by serum starvation and then exposed to a magnetic field for 18 h (H4 cells) or 24 h (MCF-7 cells), both with and without serum stimulation. The rate of DNA synthesis, taken as a measure of the cell proliferation, was determined by following the incorporation of [(3)H]-thymidine into the DNA. Three different magnetic field polarizations at both 50 and 60 Hz were used: linearly polarized (vertical); circularly polarized; and an elliptically polarized field. Magnetic field flux densities were set at 500, 100, 20 and 2 microT (rms) for the vertical field and at 500 microT (rms) for the rotating fields. No effect of magnetic field exposure was observed on either cell growth or the initial response of cell proliferation.