Abstract
BACKGROUND: Helicobacter pylori strains possessing the cagA gene are thought to induce interleukin 8 (IL-8) in gastric mucosa. However, it is still unclear whether a relation exists between the cagA gene and the expression patterns of cytokines other than IL-8. AIMS: To investigate the relation between the cagA gene and the production of various cytokine proteins using an enzyme linked immunosorbent assay (ELISA). PATIENTS AND METHODS: In 184 patients, the cagA gene was detected by polymerase chain reaction (PCR), and levels of production of IL-1 beta, IL-6, IL-7, IL-8, IL-10, and tumour necrosis factor alpha (TNF-alpha) in antral biopsy specimens were measured by ELISA. RESULTS: Mucosal levels of IL-1 beta, IL-6, IL-8, and TNF-alpha were significantly higher in H pylori positive than in H pylori negative patients. Furthermore, the mucosal levels of IL-1 beta and IL-8 were significantly higher in specimens infected with cagA positive strains than in those infected with cagA negative strains. In H pylori positive patients, the mucosal level of IL-8 was closely correlated with that of IL-1 beta (p < 0.0001), and the mucosal level of IL-6 was closely correlated with that of TNF-alpha (p < 0.0001). CONCLUSION: These findings suggest that the ability to induce cytokines differs among the strains; cagA+ strains induce various kinds of cytokines and may cause severe inflammation, whereas cagA- strains induce IL-8 and IL-1 beta only weakly and may cause only mild inflammation. However, as most patients infected with the cagA+ strains have gastritis, these strains may not be equivalent to ulcerogenic strains.