Immune Function and Host Defense in Rodents Exposed to 60-Hz Magnetic Fields

This study was conducted to evaluate the influence of sub-chronicexposure to pure, linearly polarized 60-Hz magnetic fields (MF)on the host immune response in mice. The experimental designwas as follows: three groups were exposed continuously (18.5hr/day) to MF at field strengths of 0.02, 2, or 10 gauss (G),one group was exposed intermittently (1 hr on/l hr off) to MFat a field strength of 10 G, and one group served as a shamcontrol. Experimental endpoints included spleen and thymus weightsand cellularity, antibody-forming cell (AFC) response, delayed-typehypersensitivity (DTH) response, splenic lymphocyte subset analysis, susceptibility to infection with Listeria monocytogenes,and natural killer (NK) cell activity. No differences in bodyweight, lymphoid organ weight, or lymphoid organ cellularitywere ob served in any MF-exposed group in comparison to shamcontrols. Likewise, no statistically significant differenceswere found in com parisons of AFC responses. Isolated statisticallysignificant differ ences from control were observed in MF-exposedmice in the DTH assay, although no clear dose-related patternof altered activity was seen. Splenic lymphocyte subset parametersexamined were within normal limits in all groups, and no differencesbetween control and MF-exposed mice were found. Host resistanceto bacterial infection was not altered at any MF exposure examinedin this study. Finally, although apparently dose-related, statisticallysignificant alterations were observed in an initial study ofNK cell function, repeat studies failed to demonstrate a consistentpattern of alteration.