To study the effect of 50 Hz magnetic field or static magnetic fields of 0.5 mT on subsets of human CD4+ T cells (CD4+ CD45RA+ T cells and CD4+ CD45RA--T cells) in terms of cytokine release, cell proliferation and intracellular free calcium concentration after 24 and48 h of cell culture. Subsets that were more sensitive to the effects of the magnetic fields should be identified.
CD4+ T cells can be divided into different subsets on the basis of surface marker expression (e.g. CD45), and T cells can be divided into naive (CD45RA+) and memory (CD45RA-) cells.
Blood samples were obtained from eight volunteers. The samples of the T cell subsets were also stimulated by PHA.
The data showed that 0.5 mT, 50 Hz magnetic fields or static magnetic fields (2 h exposure) induced a decrease in the release and content of interferon-gamma in CD4+ CD45RA--T cell subset (compared to CD4+ CD45RA+ T cell subset). This alteration was more evident at 24 h (than at 48 h) for both magnetic fields. The release of interferon-gamma from exposed CD4+ CD45RA--T cells was significantly decreased compared to that of sham-exposed CD4+ CD45RA--T cells.
Flow cytometry analysis showed that the CD4+ CD45RA--T cell population was the most sensitive to the magnetic fields (50 Hz or static magnetic fields). The content of interferon-gamma was significantly decreased in this subset after 24 h of exposure to the magnetic fields. However, this decrease was reversed after 48 h of cell culture.
A decrease in cell proliferation and intracellular free calcium concentrations from exposure to both magnetic fields in the CD4+ CD45RA--T cell subset was also observed.
The data suggest that exposure to the magnetic fields induces a delay in the response to stimulants (PHA) and that modifications are rapidly reversible, at least after a short exposure (2 h). The results do not explain why both magnetic fields influence only one subset of the CD4+ T-cell population.