Serum-free culture of H pylori intensifies cytotoxicity

Figure 4 Analysis of the column anion exchange chromatography of the extract cultured without serum. Cell viability that represents the putative cytotoxic factor was measured for cell viability at A₄₁₅ using the WST1 method. Column eluates that represent the protein densities were monitored at A₂₈₀ for each of the filtrated fractions. Proteins were eluted with a linear gradient of 0-0.3 mol/L NaCl. A: Anion exchange chromatography of the cell extract protein at the onset of culturing without serum. Two minor dips of cell viability are indicated (arrows); B: Anion exchange chromatography of the cell extract protein approximately 50 passages (approximately 6 mo) after the onset of culturing without serum. Two clearer minor dips of cell viabilities are indicated (arrows); C: Anion exchange chromatography of the cell extract protein approximately 100 passages (approximately one year) after the onset of culturing without serum. One minor dip and one major dip are at 0.1 mol/L NaCl and 0.2 mol/L NaCl, respectively (arrows).