Context-dependent effects of high-frequency pulsed electromagnetic fields on cytokine responses in human THP-1 monocytes in vitro

High-frequency pulsed electromagnetic fields (HF-EMF) are increasingly encountered in modern environments, yet their potential immunomodulatory effects remain unclear. Here, we investigated whether L-band pulsed HF-EMF modulate cytokine responses in human THP-1 monocytes under basal conditions or during lipopolysaccharide (LPS)-induced inflammation. Cells were exposed to pulsed electric fields at 4.6 or 7.3 kV/m, with two exposure regimens applied at each intensity (intermittent 30 s bursts or continuous 1 h exposure). Cell viability, morphology and lipid peroxidation (MDA) were assessed, and cytokine secretion was profiled by cytokine array and multiplex immunoassay, complemented by PCA and correlation network analyses. HF-EMF exposure did not induce cytotoxicity or marked oxidative damage. Under LPS stimulation, HF-EMF produced subtle yet consistent shifts in cytokine patterns, with trends toward attenuation of LPS-elevated mediators including VEGF, IL-6 and CCL17/TARC at higher field intensity. In unstimulated cells, cytokine levels remained largely unchanged, except for a reproducible decrease in basal VEGF under the highest exposure condition. Overall, these data support a context-dependent immunomodulatory effect of pulsed HF-EMF in human monocytes, warranting follow-up studies in more physiological models and with refined exposure characterization. High-frequency pulsed electromagnetic fields modulate cytokine responses only under inflammatory conditions. THP-1 monocytes were exposed to high-frequency pulsed electromagnetic fields (HF-EMFs) at 4.6 or 7.3 kV/m, in the presence or absence of LPS-induced inflammation. While no cytokine secretion was induced in resting cells, HF-EMFs partially attenuated the LPS-triggered increase in VEGF, IL-6, and TARC. Principal component and correlation analyses revealed a context-dependent modulation of cytokine profiles, suggesting a potential for selective immunomodulatory effects of HF-EMFs, and supporting their possible safety under specific conditions. • Pulsed L-band HF-EMFs did not induce cytotoxicity in THP-1 monocytes. • Cytokine signatures were subtly reshaped under LPS-driven inflammation. • High-intensity exposure tended to attenuate LPS-elevated VEGF/IL-6/CCL17. • Basal cytokine release was stable, with a consistent decrease in VEGF. • Multivariate analyses supported context-dependent immunomodulation.