Comparison of Helicobacter pyloriand Escherichia coliin induction of TNF-α mRNA from human peripheral blood mononuclear cells

Purpose:To investigate the difference between the abilities of Helicobacter pyloriand Escherichia colito induce expression of TNF-α in human peripheral blood mononuclear cells (PBMC). Materials and Methods:H pyloriwas isolated from gastric biopsy specimens. The mononuclear cells were isolated from human blood, cultured, and treated with either intact or sonicated E colior H pylori, and mRNA expression for TNF-α was detected using semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). Results:TNF-α mRNA expression levels were significantly higher in PBMCs stimulated with E colicompared to those stimulated with H pyloriat 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 coliand H pylori. Conclusions:The ability of different H pyloristrains isolated from biopsy samples to stimulate TNF-α from PBMCs was significantly lower than that of E coli. Sonicated bacteria, as compared to intact bacteria, was a very poor inducer of TNF-α mRNA expression, suggesting that the conformation of lipopolysaccharides (LPS) on the outer leaflet of the outer membrane is not totally conserved in sonicated bacteria.