Temporal Dynamics of TNF-α Expression and Cell Viability in LPS-Stimulated Peripheral Blood Mononuclear Cells

Background: Lipopolysaccharide (LPS), a key component of Gram-negative bacterial membranes, activates innate immune responses through Toll-like receptor 4 (TLR4) signaling in peripheral blood mononuclear cells (PBMCs). This study aimed to evaluate the temporal dynamics of TNF-α expression and cell viability in LPS-stimulated PBMCs to understand the inflammatory and cytotoxic effects of prolonged LPS exposure. Methods: Human PBMCs were treated with increasing concentrations of LPS (10, 30, and 50 ng/mL) for 4, 8, 12, and 24 hours. TNF-α mRNA expression was analyzed using quantitative PCR, while cell viability was assessed via CCK-8 assay and microscopic imaging. Results: LPS stimulation induced a robust, dose-dependent upregulation of TNF-α expression, peaking at 4 hours and gradually declining over time. Concurrently, PBMC viability remained stable up to 12 hours post-stimulation but significantly decreased at 24 hours, particularly at higher LPS concentrations (30–50 ng/mL). Microscopic analysis revealed increased cellular aggregation and morphological changes consistent with immune activation and cytotoxic stress. Conclusion:LPS triggers early TNF-α expression in PBMCs through TLR4-mediated activation of the NF-κB pathway. However, prolonged exposure to LPS results in decreased cell viability, likely due to sustained inflammatory signaling and oxidative stress. These findings provide insight into the dual-phase response of PBMCs to LPS and underscore the importance of tightly regulated inflammation in innate immunity.