FIGURE 7.

Effect of mild alkaline hydrolysis on the capacity of LPS from lgtB⁻pagL⁺ meningococci to induce the secretion of IL-6 in MM6 cells. The production of IL-6 by MM6 cells stimulated with serial dilutions of LPS from the lgtB⁻ mutant (open circles) and the lgtB⁻ pagL⁺ mutant of N. meningitidis, which had been left untreated (squares), incubated in neutral 5% TEA at RT for 3 h (triangles) or incubated in alkaline 5% TEA at 45 °C for 3 h (inverted triangles) is shown. As control, cells were incubated without LPS in supplemented IMDM (asterisk). IL-6 concentration in supernatants was determined by ELISA. Results are the average of quadruplicate determinations. Error bars represent the standard deviation.