Natural Killer Cells

Int J Immunopathol Pharmacol. 2009 Oct-Dec;22(4):1059-66.

Natural killer cell activity decreases in workers occupationally exposed to extremely low frequency magnetic fields exceeding 1 microT.

Gobba F, Bargellini A, Bravo G, Scaringi M, Cauteruccio L, Borella P.

Department of Public Health Sciences, University of Modena and Reggio Emilia, Modena, Italy.


In a preliminary study a reduction in natural killer (NK) cell activity in peripheral blood lymphocytes (PBL) was observed in a group of workers exposed to levels of extremely low frequency-magnetic fields (ELF-MF) exceeding 1 microT. This study was performed to confirm the results. In 121 workers engaged in various occupational activities, individual ELF-MF exposure was monitored for 2 work shifts. Exposure levels were calculated as time-weighted average (TWA). Subjects were classified as Low exposure (TWA < or = 0.2 microT), Medium exposure (TWA 0.21-0.99 microT), or Higher exposure (TWA > or = 1 microT). In higher exposure workers NK activity proved significantly reduced compared to low exposure,(p<0.01). In medium exposure a reduction was also observed, but the difference was not significant. Multivariate analysis also confirmed the relation between exposure and NK activity. It has been suggested that ELF might affect tumour progression by inducing changes in the immune system: due to the role played by NK activity in host defence against cancer, the interference with the NK cell activity observed in this study is in agreement with this hypothesis. Furthermore, an increased risk for some neurodegenerative disorders has been reported in some epidemiological studies in ELF-MF-exposed workers: changes in NK function were also described in these diseases. Our results, showing the effect on NK activity of exposure exceeding 1 microT, suggest a possible mechanism for ELF-MF effects. This could open new horizons regarding the adverse long-term effects of these fields.

Sci Total Environ. 2009 Jan 15;407(3):1218-23. Epub 2008 Sep 19.

Extremely low frequency-magnetic fields (ELF-EMF) occupational exposure and natural killer activity in peripheral blood lymphocytes.

Gobba F, Bargellini A, Scaringi M, Bravo G, Borella P.

Chair of Occupational Medicine, Department of Public Health Sciences, University of Modena and Reggio Emilia, Via Campi 287, 41100, Modena (MO), Italy.


Extremely Low Frequency-Magnetic Fields (ELF-MF) are possible carcinogens to humans and some data suggest that they can act as promoters or progressors. Since NK cells play a major role in the control of cancer development, an adverse effect on ELF-MF on NK function has been hypothesized. We examined NK activity in 52 workers exposed to different levels of ELF-MF in various activities. Individual exposure was monitored during 3 complete work-shifts using personal dosimeters. Environmental exposure was also monitored. ELF-MF levels in the workers were expressed as Time-Weighted Average (TWA) values. NK activity was measured in peripheral blood lymphocytes (PBL). In the whole group the median occupational TWA was 0.21 microT. According to the TWA levels, workers were classified as low exposed (26 subjects, TWA < or =0.2 microT) and higher exposed workers (26 subjects; TWA >0.2 microT). In higher exposed workers, we observed a trend to reduce NK activity compared to low exposed, but the difference was not significant. Then we selected a subgroup of highest exposed workers (12 subjects; TWA >1 microT); no difference was observed between low and highest exposed subjects in the main personal variables. Considering both E:T ratios from 12:1 to 50:1 and Lytic Units, a significant reduction in NK activity was observed in the highest exposed workers compared to the low exposed. Multivariate analysis showed a significant negative correlation between exposure and LU, while no correlation was evidenced with other personal characteristics. ELF-MF are considered possible carcinogens, and existing data suggest that they can act as promoters. Due to the role of NK activity in host defence against cancer, the results obtained in this study in workers exposed to ELF-MF levels exceeding 1 microT are in agreement with this hypothesis, and support the need for further investigation in this field.

Electromagn Biol Med. 2006;25(2):79-85.

Suppression of natural killer cell activity on Candida stellatoidea by a 50 Hz magnetic field.

Canseven AG, Seyhan N, Mirshahidi S, Imir T.

Department of Biophysics, Gazi University Medical Faculty, Ankara, Turkey.


Exposure to electromagnetic fields (EMF) is ubiquitous for almost all individuals living in industrialized countries. Epidemiological and laboratory studies suggest that exposure to Extremely Low Frequency (ELF) EMF increase cancer risk. The immune system functions as one of the body’s main protective mechanisms, and Natural Killer (NK) cells are a subset of lymphocytes that can destroy several types of tumor cells. In this study, we investigated, NK cell activity after exposure to a 50 Hertz (Hz), 2 mT magnetic field generated by a Helmholtz Coil. Nineteen male, 10-12 week old guinea pigs were used, and NK cytotoxic activity of splenocytes was measured in vitro by natural anticandidial colorimetric index. The Mann-Whitney U test was applied for statistical analysis. NK cell cytotoxic activity was decreased in exposed compared to controls. Our data suggests that part of the immune system, the NK cell, can be suppressed by a 50 Hz magnetic field.

Radiats Biol Radioecol. 2003 Sep-Oct;43(5):531-4.

Activity of natural killer cells of the spleen of mice exposed to low-intensity of extremely high frequency electromagnetic radiation.

[Article in Russian]

Oga? VB, Novoselova EG, Cherenkov DA, Fesenko EE.

Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, 142290 Russia.


The dose dependence of natural killer (NK) cell activity from mouse spleen upon action of low-intensity millimeter waves in the exposure range from 5 to 96 hours was studied. It has found an increase of NK activity by 24 hours posttreatment that returned to normal level in a day after the cessation of the irradiation. Also the stimulation of isolated NK cell activity after millimeter waves treatment within 1 hour was revealed.

Biofizika. 1999 Jul-Aug;44(4):737-41.

Stimulation of murine natural killer cells by weak electromagnetic waves in the centimeter range.

[Article in Russian]

Fesenko EE, Novoselova EG, Semiletova NV, Agafonova TA, Sadovnikov VB.

Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region, Russia.


Irradiation with electromagnetic waves (8.15-18 GHz, 1 Hz within, 1 microW/cm2) in vivo increases the cytotoxic activity of natural killer cells of rat spleen. In mice exposed for 24-72 h, the activity of natural killer cells increased by 130-150%, the increased level of activity persisting within 24 h after the cessation of treatment. Microwave irradiation of animals in vivo for 3.5 and 5 h, and a short exposure of splenic cells in vitro did not affect the activity of natural killer cells.