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ette-Guérin (Mycobacterium bovis BCG) in protecting humans against tuberculosis has prompted a search for the mechanisms through which BCG induces chemokines. In this study, our experiments were designed to determine the role of the transcription factor nuclear factor-kB (NF-kB) and intracellular calcium in the production of interleukin (IL)-8, a main chemotactic factor, by human-derived monocytic cell line U937 and by a human epithelial HEp-2 cell line infected with M. bovis BCG. Methods : The concentrations of IL-8 in culture supernatants of U937 cells or HEp-2 cells infected with M. bovis BCG were determined by enzyme-linked immunosorbent assay. We used sulfasalazine and curcumin, which are well-described inhibitors of NF-kB activity, and we used ethylenediamine tetraacetic acid to deplete extracellular Ca or used the cell-permeable agent 1,2-bis (2-aminophenoxy) ethane-N ,N ,N ?,N ?-tetraacetic acid tetra (acetoxymethyl) ester to chelate releasable intracellular stores of Ca in order to investigate the mechanisms through which M. bovis BCG induces IL-8 secretion in our system. Results : The enzyme-linked immunosorbent assay showed that IL-8 protein secretion was elevated in M. bovis -infected cell lines. This effect was statistically significant (pB/ 0.01). When calcium influx was suppressed in M. bovis -infected cell lines, IL-8 secretion was inhibited. Notably, specific inhibitors of NFkB (sulfasalazine and curcumin) inhibited M. bovis induced IL-8 secretion from U937 cells or HEp-2 cells. Conclusions : Collectively, these results indicate that activation of NF-kB is an important signal transduction pathway in M. bovis -induced IL-8 secretion in monocytic or epithelial cells. Furthermore, the results showed that calcium influx had a direct effect on IL-8 secretion in U937 cells or HEp-2 cells infected with M. bovis .