報告書番号

U00036

タイトル（和文）

商用周波磁界と免疫系（その７） --1.4～700 μTrms 回転円磁界曝露がマウスマクロファージとBリンパ球のサイトカイン産生に与える影響--

タイトル（英文）

Power frequency magnetic field and immunologic system(part7)-Effects of 1.4 to 700 μTrms circularly polarized, magnetic field exposure on cytokine productions from mice macrophage and B-lymphocyte-

概要 （図表や脚注は「報告書全文」に掲載しております）

免疫系は抗腫瘍能を担うため、磁界影響の有無を解明する必要がある。病原菌の体内進入を模擬し、マクロファージとBリンパ球を免疫学的に刺激するために、1群10匹のBALB/cマウスに、50 Hz、1.4～700 μTrms の回転円磁界を3～12週間曝露し、曝露直後にリポポリサッカライド（LPS）を腹腔より投与した。90分後に血清、脾臓、肺を採取し、免疫情報伝達物質であるサイトカイン（TNF-α、IL-6、IL-1β、IL-10、IL-12）の量を測定し、曝露群と対照群の差を統計学的に検定した。実験は、同条件の曝露を3回繰返し盲検法で実施した。496回の測定のうち3回に統計学的に有意な変化が見られたが、変化は曝露強度や期間とは無関係で、増減の方向に一貫性がなく、繰り返し実験では再現しなかった。この結果から、本実験条件下ではLPS刺激下マウスのサイトカイン産生に磁界影響のないことが明らかになった。

概要 （英文）

This report describes a possible magnetic field (MF) effect on production of cytokines, polypeptide hormones secreted from immune cell, that regulate a variety of immunological processes such as endotoxin shock or anti-tumor activity. We employed an experimental model of an enhanced immune function in vivo that is the systematic production of lipopolysaccharide (LPS) induced-cytokines originated mainly from macrophage and B-lymphocyte. Objective of the present study is to examine if 50 Hz, 1.4 to 700 μTrms, circularly polarized MF exposure for 3 to 12 weeks can alter the cytokine secretions in mice. Groups of 10 male BALB/c mice, 6 weeks of age, were specific pathogen free and housed in our MF exposure facilities that were barrier system. Immediately after the expsoure, mice were treated with an intaperitoneal injection of 10 mg of LPS. They were sacrificed 90 min after the injection, and induced 7 cytokines, which were interleukin-1 beta (IL-1β), IL-6, IL-10, IL-12 and tumor necrosis factor-alpha (TNF-α), in sera, spleens and lungs were measured with enzyme-linked immunosorbent assay. Mean values of MF-exposed and control groups were statistically evaluated if the group difference was significant. Exposure and control experiments were conducted simultaneously with a batch of animals in a blind fashon. Background 50 Hz MF was less than 0.02 μTrms. Exposures were performed over 22 hours a day, 7 days a week. Bases of these cytokine productions in the two groups were first determined without exposing MF in the facilities. No difference among four identical facilties in either cytokine level in three organs was evident. Thereafter, mice were exposed to 1.4, 70, 350 or 700 μTrms MF for 3, 6, or 12 weeks. In addition, 12 weeks exposure followed by one week of sham exposure was conducted to examine to find any recovery process exist. Exposure experiments were repeated three times under the same condition to confirm reproducibility of results obtained. Three out of 469 cytokine measurements indicated statistically significant difference between MF-exposed and control goup values: decreases in serum IL-6 from mice exposed to 1.4 μTrms for 6 weeks and in spleen from mice exposed to 1.4 μTrms for 12 weeks followed by one week sham exposure, and increase in spleen IL-12 from mice exposed to 70 μTrms for 12 weeks. The rest of cytokine measurements did not show any significant effect of MF exposure. Observed changes, however, were not considered to be biologically significant, because the changes were not dose-related nor exposure time-dependent, directions of the changes were not biologically explainable, organ or cytokine specificity did not occur, and reproducibility was not preserved. Obtained data therefore suggest that the MF exposure did not affect the LPS-induced cytokine productions in mice under experimental conditions we employed.

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