With the expanding usage of various devices, which emit static and extremely low-frequency magnetic fields, increases the number of biomedical reports on their influence as well as demand for suitable experimental exposure systems. Experimental setups range from permanent magnets through Helmholtz coils to solenoids; however, almost all of them provide relatively weak magnetic fields of up to 10 mT. Widespread use of devices such as MR scanners imposes intentional as well as unintentional exposure to stronger fields. A typical solenoid produces stronger although less homogeneous field than the most commonly used experimental equipment composed of sets of coaxial coils. In order to provide scalable, relatively strong, low-varying field within experimental volume that is large enough for in vivo as well as in vitro experiments modified solenoids are considered. Variation of the field was reduced by modifying the shape and size of solenoid's cross section. Modified solenoids were modeled analytically, numerically, and as a prototype. Solenoid geometries were optimized for maximal field performance and minimal power consumption. The optimal modified solenoids scalable to desired sizes of the experimental volume and values of maximal magnetic induction intensities are offered. The suggested solenoid modification method can decrease field variation as much as 10.6 times.

In contrast to electromagnetic fields, static magnetic fields (SMFs) have not been extensively studied in terms of their potential health consequences. Although upward- and downward-oriented magnetic poles may cause various biological effects, only the pole with the upward orientation has been mainly investigated. Considering that the interaction of antigen-presenting cells (APCs) and T lymphocytes is crucial to trigger an immune response, we assessed the effect of long-term exposure of human T lymphocytes and dendritic cells (DCs) to moderate strength SMFs of different orientations focusing on the cytokine profile of activated T cells. Cultures of allogenic T lymphocytes and DCs (immature and matured by TLR3 and TLR7 agonists) were continuously exposed to four SMFs. The intensity of the applied field was 1 militesla (mT) or 56 mT of the upward- and downward-oriented pole of the SMF. Cell culture supernatants were assayed for IFN-γ, IL-4, IL-17, TNF-α, TNF-β, IL-1 β, IL-6, IL-8, and IL-10 by ELISA or flow cytometry. The upward-oriented 56 mT SMF significantly increased the release of IFN-γ and TNF-β (both p < 0.05) in the cell culture supernatants of T cells and immature DCs. In contrast, the same cultures exposed to the upward-oriented 1 mT SMF showed significantly elevated levels of IL-17 (p < 0.05). The levels of IL-4, TNF-α, IL-1 β, IL-6, IL-8, and IL-10 were not affected by the upward-oriented SMF. The downward-oriented 56 mT SMF increased TNF-α release when T cells were stimulated with mature DCs. The production of other cytokines was unchanged by the downward-oriented SMF. These findings demonstrate for the first time different in vitro biological effects of upward- and downward-oriented static magnetic fields on the cytokine production of T cells activated by DCs, helping to better understand SMF effects on the immune system and suggesting that the selective SMF effect on the immune response could have potential therapeutic effects in different immune-mediated disorders.