Abstract: Objective：To explore the possible mechanism of the anti-β₂GPI/β₂GPI complex stimulating monocyte cell line THP-1 to express inflammatory cytokines IL-6, IL-8 and TNF-α. Methods: The expressions of IL-6, IL-8 and TNF-α mRNA in THP-1 cells following stimulating by anti-β₂GPI/β₂GPI complex at different points in time (0.5, 1, 1.5, 2 and 6 h, respectively) were determined with real-time PCR, and their protein levels were measured with immunofluorescence and Western blot. The interference of inhibitor of TLR4 signal transduction pathway (TAK-242) for the effects of anti-β₂GPI/β₂GPI complex on THP-1 cells were investigated using real-time PCR and Western blot assays. Results: The expression levels of IL-6, IL-8 and TNF-α mRNA in THP-1 cells stimulated with 100 μg/mL of anti-β₂GPI/β₂GPI complex were increased with the time of treatmenttime, and reached peak values at 2 hours after the stimulation (P<0.01). The protein levels of IL-6, IL-8 and TNF-α were also significantly increased as demonstrated with immunofluorescence and Western blot. However, the expressions of IL-6, IL-8 and TNF-α mRNA in THP-1 cells induced by anti-β₂GPI/β₂GPI complex were inhibited obviously by 5 μmol/L of TAK-242. Conclusion: Anti-β₂GPI/β₂GPI complex may stimulate THP-1 cells to express inflammatory cytokines IL-6, IL-8 and TNF-α via TLR4 signal transduction pathway, which involves the pathogenesis of antiphospholipid syndrome.