Elsevier

Toxicology

Volume 187, Issues 2–3, 3 May 2003, Pages 171-181
Toxicology

Immunomodulatory effects of l-carnitine and q10 in mouse spleen exposed to low-frequency high-intensity magnetic field

https://doi.org/10.1016/S0300-483X(03)00050-7Get rights and content

Abstract

In the current study, we have investigated the bioeffects of repeated exposure to low-frequency (50 Hz) high-intensity (20 mT; 200 G) electromagnetic field (EMF) on some immune parameters in mice. The animals were exposed to EMF daily for 30 min three times per week for 2 weeks. We also studied the possible immunomodulatory effects of two anti-radical substances known to have non-specific immunostimulant effects namely, l-carnitine (200 mg/kg body weight i.p.) and Q10 (200 mg/kg body weight, p.o.). Both drugs were given 1 h prior to each EMF exposure. Immune endpoints included total body weight, spleen/body weight ratio, splenocytes viability, total and differential white blood cell (WBCs; lymphocytes, monocytes, neutrophils) counts, as well as the lymphocyte proliferation induced by the mitogens; phytohaemagglutinin (PHA), concanavalin-A (Con-A) and lipoploysaccharide (LPS). Magnetic field decreased splenocyte viability, WBCs count, as well as mitogens-induced lymphocyte proliferation. l-carnitine, but not Q10 could ameliorate the adverse effects of EMF on the vast majority of the immune parameters tested, suggesting a possible immunoprotective role of l-carnitine under the current experimental conditions.

Introduction

With the increased urbanisation and the fact that electrical appliances are commonly used in our daily life, human beings and many other living organisms as well, are inevitably subject to the frequent exposure to low-frequency electromagnetic fields (EMFs) (Li and Chow, 2001). EMFs range from cosmic rays to the static magnetic fields of earth. Between these extremes is visible light, separating the whole range into ionising and non-ionising radiations (Jahn, 2000). Extremely low EMFs, to which belongs the frequency used in the current study, lie in the range of 3–3000 Hz (Repacholi and Greenbaum, 1999). Alternating current has a frequency of 60 Hz in the USA and Canada, whereas it reaches 50 Hz in other countries. Magnetic field intensity is measured in international units called Tesla (T) or in the American units called Gauss (G). One unit Tesla equals 104 Gauss (Repacholi and Greenbaum, 1999).

Biological effects of low-frequency fields have been studied during the last three decades. Unfortunately, results of epidemiological studies in this research area have been contentious; results indicated that there is a link between the prevalence of adverse biologic effects and low-frequency field's exposure, but there is not a significant association between insult and exposure (Anonymous, 1999, Orbach-Arbouys et al., 1999, Caplan et al., 2000). Both low- and high-intensity low-frequency fields were subject to extensive investigations in an attempt to settle risk-assessment guidelines for the human exposure.

Though residential exposure to low-frequency EMFs such as those from high-voltage powerlines results in low-intensity fields, possibility of human exposure to high-intensity fields has been increased lately due to the increased extent of modernisation. Actually, some electric devices such as the magnetic resonance image (Schenck, 2000) could induce fields that may reach more than 1000-fold the intensity of the residential levels of EMFs. Further, human beings could be exposed to high-intensity magnetic fields that may reach thousands Gauss from some magnetic belts and magnetic pads, as well as steel-belted radial tires (Milham et al., 1999).

An array of experimental studies have been conducted in different species to evaluate the effects of low-frequency (50–60 Hz) waves with different field intensities (0.1–1000 μT) on immune system. The available literature on immune function has both strengths and weaknesses. Most of the studies conducted to date have investigated a wide variety of immune function endpoints, including immune system structures, cell- and humoural-mediated immunity, and innate immunity (Mevissen, 1999). These studies have been conducted in diverse species including mice, rats, baboons, sheep and humans. However, data so far obtained revealed debatable conclusions.

Tenforde and Shifrine (1984) have demonstrated that following a 6-week exposure of LAF1/J mice to a 1.5 Tesla stationary magnetic field no significant differences were observed in the responses of spleen lymphocytes between exposed and control groups. Also, Ramoni et al. (1995) have reported that 50-Hz Sinusoidal magnetic fields with flux intensities up to 10 mT do not affect the cytotoxic activity of human natural killer (NK) cells. Further, no effects of linearly polarised 60-Hz magnetic fields up to 10 G intensity were found on the host immune response in mice (House et al., 1996).

Contrariwise, a 6-week exposure to 50 μT (0.5 G) field resulted in reductions of surface marker antigens, interlukin 2 receptor expression, and proliferative response to Pokweed mitogen in blood lymphocytes derived from baboons (Murthy et al., 1995). Tremblay et al. (1996) have also documented that in vivo exposure of Fisher rats for 6 weeks to 60-Hz magnetic field with intensity up to 2000 μT induced significant immunological perturbations on effector cells of both natural and adaptive immunity in a dose-dependent manner. Besides, Mevissen et al. (1998) have reported that exposure of female Sprague–Dawley rats to 50-Hz, 100 μT magnetic field for 13 weeks induced complex effects on the mitogenic responsiveness of T cells, which may lead to impaired immune surveillance after long-term exposure.

l-Carnitine is a naturally occurring quaternary ammonium compound, which is endogenously synthesised in man and also found in the diet (Goa and Brogden, 1987). It is an essential cofactor of several enzymes necessary for the transformation of long-chain fatty acids, and also acts as a scavenger of oxygen free radicals in mammalian tissues (Izgut-Uysal et al., 2001). l-carnitine has proven efficacy in ischemic heart probably by selectively reducing the accumulation of mitochondrial long-chain acyl-CoA, as well as long-chain acylcarnitine (Fujisawa et al., 1992). The observation that leukocytes, including peripheral blood mononuclear cells (PBMNs), are enriched in carnitines (Deufel, 1990) first suggested that l-carnitine and its congeners might regulate the immune networks. Previous reports have demonstrated the enhancement of immune responses by l-carnitine supplementation (De Simone et al., 1982a, De Simone et al., 1985, Monti et al., 1989). In addition, l-carnitine has been shown to protect cells against toxicity of reactive oxygen intermediates (Monti et al., 1992). Famularo et al. (1994) have demonstrated anti-apoptotic effects of l-carnitine and its congeners in vitro. A reduced pool of carnitines has been found in either serum or tissues, or both, in disorders with unregulated immune responses such as the chronic fatigue syndrome (Majeed et al., 1995) and septic shock (Famularo et al., 1995), as well as AIDS patients (Famularo and De Simone, 1995). This further lends support to the view that a normal endogenous pool of carnitines is crucial to the maintenance of normal immune system.

Coenzyme Q (Q10) is well defined as a crucial component of the oxidative phosphorylation process in mitochondria which converts the energy in carbohydrates and fatty acids into ATP to drive cellular machinery and synthesis. Q10 can undergo oxidation/reduction reactions in other cell membranes such as lysosomes, Golgi apparatus and plasma membranes. It has been shown that Q10 could have a function in redox control of cell signalling and gene expression as evidenced from its role in cell growth stimulation, inhibition of apoptosis, control of thiol groups, formation of hydrogen peroxide and control of membrane channels (Crane, 2001). Q10 was found to completely suppress the elevation in lipid peroxide level induced by LPS in mouse liver (Suzuki, 1991). Being non-specific stimulant of the immune host defence system (Bliznakov, 1978), Q10 has been observed to protect against tumour growth and to enhance viral immunity in experimental animals, as well as it elicited remarkable improvement in AIDS patients (Tanner, 1992).

The current study was conducted to investigate the biological effects of low-frequency (50 Hz) high-intensity (20 mT; 200 G) electromagnetic field on some immune parameters in mice. Though this intensity is more than 10-fold the residential exposure levels from high-voltage powerlines, it is about 1/10–1/25 times the magnetic fields from some magnetic belts and magnetic pads, as well as magnetic resonance instruments. Possible protection by two non-specific immunostimulants to the host defence, namely l-carnitine and Q10, was also assessed. Parameters undertaken in the present work were: total body weight and relative spleen/body weight ratio, total and differential counts of white blood cells (WBCs), viability of splenocytes, as well as lymphoproliferation assays using lectins-induced 3[H]thymidine incorporation into splenocytes as a measure of DNA synthesis and consequently a measure of lymphocyte proliferation.

Section snippets

Animals

Male healthy Swiss albino mice weighing 20–25 g were obtained from the National Centre for Radiation Research and Technology (NCRRT), Cairo, Egypt. The animals were housed in the animal facility of the Pharmacy College, Al-Azhar University, Cairo, Egypt, at 23±1 °C and 55% humidity with 12-h light:12-h dark cycle. The mice were fed a standard pellet diet (El-Nasr Co., Abou-Zaabal, Cairo, Egypt), and water ad libitum. The animal experiments have been approved by the Committee of Animal

Results

The effects of magnetic field alone and in combination with l-carnitine or Q10 on the immune parameters tested in mouse blood and spleen are compiled in Table 1.

Neither l-carnitine nor Q10 had any effects on the immune parameters measured in normal mice.

Magnetic field significantly decreased the animal body weight by 7% compared with control animals, but it had no effect on spleen relative weight. Pre-treatment with either l-carnitine or with Q10 did not add to the effect of magnetic field on

Discussion

One of the most contentious issues in the scientific community today is that of the biological effects of EMFs, and whether or not they are adversely affecting our health. For decades, researchers have been concerning about the bioeffects of low-frequency, low-intensity EMFs, which are comparable to both residential and occupational exposure levels in many work fields. Due to extensive modernisation and sophistication of our daily life, high intensity fields from some EMF-producing instruments

References (54)

  • G. Famularo et al.

    Aopotosis, anti-apoptotic compounds and TNF-alpha release

    Immunol. Today

    (1994)
  • R.V. House et al.

    Immune function and host defence in rodents exposed to 60 Hz magnetic fields

    Fundam. Appl. Toxicol.

    (1996)
  • J. Jajte et al.

    Protective effect of melatonin against in vitro iron ions and 7 mT 50 Hz magnetic field-induced DNA damage in rat

    Mutant Res.

    (2001)
  • S.H. Li et al.

    Magnetic field exposure induces DNA degradation

    Biochem. Biophys. Res. Commun.

    (2001)
  • M.I. Luster et al.

    Risk assessment in immunotoxicology. Sensitivity and predictability of immune tests

    Fundam. Appl. Toxicol.

    (1992)
  • D. Monti et al.

    Apoptosis-programmed cell death: a role in the ageing process

    Am. J. Clin. Nutr.

    (1992)
  • M. Simko et al.

    Stimulation of phagocytosis and free radical production in murine macrophages by 50 Hz electromagnetic fields

    Eur. J. Cell. Biol.

    (2001)
  • H.A. Tanner

    Energy transformations in the biosynthesis of the immune system: their relevance to the progression and treatment of AIDS

    Med. Hypotheses

    (1992)
  • Anonymous, 1999. Exposure to power-frequency magnetic fields and the risk of childhood cancer. UK Childhood Cancer...
  • B. Brocklehurst et al.

    Free radical mechanism for the effects of environmental electromagnetic fields on biological systems

    Int. J. Radiat. Biol.

    (1996)
  • P. Conti et al.

    Reduced human lymphocyte blastogenesis and enhancement of adenosine triphosphate (ATP) by l-carnitine

    Mol. Cell. Biochem.

    (1994)
  • F.L. Crane

    Biochemical functions of coenzyme Q10

    J. Am. Coll. Nutr.

    (2001)
  • C. De Simone et al.

    Vitamins and immunity: II. Influence of l-carnitine on the immune system

    Acta Vitaminol. Enzymol.

    (1982)
  • C. De Simone et al.

    Reversibility by l-carnitine of immunosuppression induced by emulsion of soya bean oil, glycerol and egg lecithin

    Drug Res.

    (1982)
  • C. De Simone et al.

    Lipids and the immune system are influenced by l-carnitine. A study in elderly subjects with cardiovascular diseases

    Int. J. Immunother.

    (1985)
  • T. Deufel

    Determination of l-carnitine in biological fluids and tissues

    J. Clin. Chem. Clin. Biochem.

    (1990)
  • L. Devevey et al.

    Can 50 Hz magnetic fields alter iron metabolism and induce anaemia

    Int. J. Radiat. Biol.

    (2000)
  • Cited by (32)

    • Electromagnetic fields may act via calcineurin inhibition to suppress immunity, thereby increasing risk for opportunistic infection: Conceivable mechanisms of action

      2017, Medical Hypotheses
      Citation Excerpt :

      In other words, many of the biological effects produced in many of these short-term exposure conditions using power densities at levels higher than we would normally experience in everyday life may very well be mimicked by present-day long-term exposures to lower power densities many of us are currently encountering. Experimental immunological research studies have demonstrated that nonthermal EMF exposures can affect immune-specific organs [66–70], innate and adaptive immune cell activity [30,31,68,69,71–73,77–79], antibodies [69,82,83], cytokines [87–89,95], and enzymes [65,131], with other research studies showing effects on the autoimmune system [86,91], cellular Ca2+ uptake [30,31], augmentation of chemical toxicity [84], food sensitivities [92], and increased free-radical production [109–211]. The same opportunistic infections induced as side effects in transplant recipients taking immunosuppressant calcineurin inhibitors to prevent organ rejection — reactivated viral (EBV, CMV, Coxsackie, etc.), candida, mold, bacterial (mycoplasma), and parasitic (toxoplasmosis) infections — have also been uncovered in a number of what have been described as neuro-immune dysfunction syndromes (NIDS)[213]: e.g., CFS, ASD, ADHD, and Alzheimer’s disease [AD], [214–264] etc.

    • Role of l-carnitine in the modulation of immune response in aged rats

      2008, Clinica Chimica Acta
      Citation Excerpt :

      Based on this a dose of 300 mg/kg body weight was chosen for the present study. Moreover l-carnitine at a concentration of 200 mg/kg body weight i.p. was reported to improve immune responses in mice exposed to low frequency high intensity magnetic field [36]. From the results of the current study it could be suggested that l-carnitine administration at a dose of 300 mg/kg body weight is found to be effective in improving immune functions in aged animals.

    View all citing articles on Scopus
    View full text