LPS-induced IL-8 production is BTC dependent in human lung cancer cells A549. A549 cells were pretreated with anti-BTC neutralizing antibody (Neu-Ab) for 2 h. Subsequently, cells were stimulated with LPS (1 μg/ml) for 4 h. Total RNA was extracted and subjected to reverse transcription followed by qPCR to detect IL-8 mRNA (A). IL-8 in cell-free supernatants after 24 h stimulated by LPS were assayed using sandwich ELISA (B). A549 cells were then stimulated with BTC (0.01, 0.1 and 1 μg/ml) for 4 h to detect IL-8 mRNA (C) or 24 h to detect its secretion of IL-8 in supernatants (D). Each data point represents mean ± SEM of three experiments. * and ** stand for P- values less than 0.05 and 0.01, in comparison with untreated control cells, and + and ++ stand for P - values less than 0.05 and 0.01, as compared to LPS (1 μg/ml) and DMSO, respectively.