Extremely low frequency electromagnetic field exposure does not modulate toll-like receptor signaling in human peripheral blood mononuclear cells.

The effects of extremely low frequency electromagnetic fields (ELF-EMF) on human health remain unclear. It has been reported that ELF-EMF may modulate the innate immune response to microorganisms in animal models and mammalian cell-lines. With the recently gained insight in innate immune signaling and the discovery of pattern recognition, we aim to study whether ELF-EMF modulates innate inflammatory signaling pathways. We used human peripheral blood mononuclear cells (PBMCs), isolated from blood from healthy volunteers, which we stimulated with specific TLR2 and TLR4 ligands, and with several microorganisms. The cells were subsequently exposed in B(dc)=3 μT to a highly controlled and standardized ELF-EMF signal (20-5000Hz, B(ac)=5 μT, 30 min) and cytokine production was measured at different time points after stimulation. No significant difference in immune response, as reflected by IL-1β, IL-6, TNFα, IL-8 and IL-10 production, could be detected after stimulation with LPS (TLR4 ligand), Pam3Cys (TLR2 ligand) or a panel of heat killed microorganisms: Mycobacterium tuberculosis, Salmonella typhimurium, Candida albicans, Aspergillus fumigatus and Staphylococcus aureus (multiple TLR ligands). We therefore conclude that under our experimental conditions, ELF-EMF does not modulate the innate immune response of human primary cells after TLR stimulation in vitro.