Potential role of CagA in the inhibition of T cell reactivity in Helicobacter pylori infections

The pathogenicity of chronic gastroduodenal diseases is very often related to Helicobacter pylori infections. Most H. pylori strains carry the cagA ge ne encoding an immunodominant 120- to 128-kDa protein which is considered a virulence marker. The majority of CagA-positive H. pylori isolates also pr oduce a 95-kDa protein cytotoxin (VacA) causing vacuolation and degradation of mammalian cells. In our previous study we have shown that live H. pylor i bacteria and their sonicates inhibit PHA-driven proliferation of human T lymphocytes. The H. pylori CagA and VacA proteins were suspected of a paral yzing effect of H. pylori on T cell proliferation. In this report, by using isogenic H. pylori mutant strains defective in CagA and VacA proteins, we determined that CagA is responsible for the inhibition of PHA-induced proli feration of T cells. (C) 2000 Academic Press.