[ EMF-Link Home
| Online Store
| Comments
| Up One Level ]
| TITLE: | Effect of 60-Hz Magnetic Fields on Lymphoid Phenotype | ||
| Principal Investigator |
Andrew A. Marino, Ph.D. | Louisiana State University Medical Center, School of Medicine | |
| Health Relevance |
Cancer | ||
| Research Categories |
Toxicology Studies Using Whole Animals | Short Term Studies | Immunosuppression |
| FY95 Funds | R01ES05928 $ 223,002 | Start Date 09/25/95 | End Date 08/31/98 |
| Rationale and Summary |
A correlation between exposure to electromagnetic fields (EMF) in the environment and human
disease, particularly cancer, has been reported, but direct links between exposure and disease have
not been established in animal models, despite many reports of EMF-induced physiological changes
in exposed animals. The long-term objective of this research is to understand how EMF exposure is
linked to human disease. Our overall hypothesis is that EMF can induce an immunodeficient state
(compared with the immune status of the organism if it had not been chronically exposed), thereby
resulting indirectly in increased incidence of disease.
In the work proposed here, we will use a mouse model to determine whether exposure to 60-Hz magnetic fields for up to 25 weeks produces phenotypic and/or quantitative changes in various lymphoid components that are consistent with immunosuppression. Considering the important role natural killer cells play in host resistance to tumor growth and metastasis, particular focus will be placed on determining whether chronic EMF exposure results in alterations in the number and/or function of these important effector cells. We hypothesize that immunosuppression will occur at higher magnetic-field doses (magnetic field strength x exposure time). |
||
| Experimental Design and Exposure Conditions |
Epidemiological studies indicate that exposure to electromagnetic fields (EMF) in the environment increases the risk for disease, particularly cancer. Pre-transcriptional models have been proposed to explain the observations: In this view, EMF-related carcinogenesis occurs as a consequence of field induced changes in membrane-bound glycoproteins leading to changes in intercellular second- messenger systems and gene expression in the affected cell. The hypothesis underlying the work proposed here is that EMF effects are post-transcriptional with respect to the EMF-detecting cell: Fields are detected by a neural electrogenic, membrane-bound protein, and the resulting subthreshold changes in membrane potential modify ongoing oscillatory behavior thereby constituting an afferent signal to the thalamus. The resulting efferent signals mediate a nonspecific adaptive response to the EMF; chronic activation of the adaptive system adversely affects immunosurveillance by natural kill (NK) cells, thereby making the occurrence of clinical disease more likely than would have been the case in the absence of EMF exposure. The prediction of immunosuppression in chronically exposed animals will be tested in the proposed work by exposing mice to EMF, and measuring the effect on the phenotype of the lymphoid cells. Separate groups of male and female mice will be exposed to 5, 50, 500 mG , and 5 gauss, 60 Hz for periods ranging from 1 day to 25 weeks, and the number of NK cells, T cells, and B cells in the spleen, blood, lymph nodes and bone marrow will be determined as a function of intensity and duration of field exposure, and compared with values measured in sham-exposed animals. 51Cr-release assays will be used to measure the effect of field exposure on the lytic function of constitutive and inducible (with polyinosinic:polycytidyllic) NK cells, and cytotoxic T lymphocytes generated in mixed lymphocyte cultures from the spleen. In addition, an in vitro assay involving IL-2 activation of splenic NK cells to lyse tumor targets will be used to characterize the inducibility of lymphocytes from exposed animals. | ||
| Quality Assurance Measures |
Homogeneous fields will be generated using a coil arrangement, and a computer-based system will
monitor temperature, field, and coil current, and provide documentation of environmental
conditions. Coil current will be analyzed for the occurrence of harmonic and aharmonic distortion,
and to document the absence of transients.
All tissues and cells will be coded and randomized after collection to ensure that the personnel making the measurements and performing the assays are blinded regarding whether the samples are obtained from exposed or control animals. A consultant will be hired to provide an independent assessment of the overall suitability of the exposure system. |
||
| Results and Discussion |
This project is newly funded, effective 9/95. | ||
| Recent Publications |
None. | ||