RESUMO
PURPOSE: To investigate the difference between the abilities of Helicobacter pylori and Escherichia coli to induce expression of TNF-alpha in human peripheral blood mononuclear cells (PBMC). MATERIALS AND METHODS: H pylori was isolated from gastric biopsy specimens. The mononuclear cells were isolated from human blood, cultured, and treated with either intact or sonicated E coli or H pylori, and mRNA expression for TNF-alpha was detected using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). RESULTS: TNF-alpha mRNA expression levels were significantly higher in PBMCs stimulated with E coli compared to those stimulated with H pylori at the same number and identical conditions (P < .001). The results also suggest that sonicated bacteria were significantly (P < .001) less stimulatory for PBMCs than intact bacteria for both E coli and H pylori. CONCLUSIONS: The ability of different H pylori strains isolated from biopsy samples to stimulate TNF-alpha from PBMCs was significantly lower than that of E coli. Sonicated bacteria, as compared to intact bacteria, was a very poor inducer of TNF-alpha mRNA expression, suggesting that the conformation of lipopolysaccharides (LPS) on the outer leaflet of the outer membrane is not totally conserved in sonicated bacteria.
