FIG. 6.

Effect of removal of meningococcal KDO₂ by acid hydrolysis on TNF-α release by human macrophages. Meningococcal LOS of parent strain NMB (Table 1) was hydrolyzed with 1% acetic acid (pH 2.8) or with 12 mM acetic acid (pH 3.4) or 1 M acetate buffer (pH 4.3) or was treated with PBS (pH 7.4). TNF-α release from THP-1 cells induced with hydrolyzed LOS at a concentration of 0.56 pmol/ml was measured. Lipid A of the kdtA mutant and unstimulated cells were used as controls. Error bars represent SD from the mean.