Effects of nuclear factor kappa B (NF-κB) inhibitors on S100A8/A9-mediated cytokine production. Monocytes (1 × 106 cells per ml in culture medium with 10% fetal calf serum), after two-hour pretreatment with or without the inhibitors of NF-κB activation (1 μM), 1-pyrrolidinecarbodithioic acid (PDTC), and Nα-tosyl-phenylalanylchloromethylketone (TPCK), were stimulated for 24 hours with or without S100A8/A9 (1 or 10 μM) in the presence of polymyxin B. Culture supernatants were measured for tumor necrosis factor alpha (TNF-α) concentrations by enzyme-linked immunosorbent assay. Values are the mean ± standard error of the mean. n, number of samples tested.