Role of strain type, AGS cells and fetal calf serum in Helicobacter pyloriadhesion and invasion assays

In a human gastric biopsy specimen, 30%: of adhering helicobacter pylori st rain AF1 (cagA and VacA positive) was associated with adhesion pedestals. I n all AGS cell assay, only a few percent of this type I strain was found to be associated with adhesion pedestals. Nevertheless, a larger proportion o f the type 1 strain was found to invade AGS cells (P < 0.03) and to attach with depressions in the AGS cell membrane (P < 0.03) than a type II strain (cagA and VacA negative). Incubation of AGS cells and H. pylori without add ing. fetal calf serum (FCS) to the culture medium increased actin accumulat ions (FITC-phalloidin stained) beneath adhering H. pylori , and decreased H . pylori invasion of AGS cells significantly (P < 0.01). However, no increa se in the number of adhesion pedestals was observed by electron microscopy. Proteinase It treatment of FCS eliminated the H pylori i invasion promotin g effect (P < 0.01). Our results suggest differences in the ability of IL p ylori i to induce adhesion pedestals in human gastric epithelial cells and in AGS cells, but a correlation between adhesion pedestal formation in vivo and H. pylori invasion can be speculated. In addition, H. pylori invasion into AGS cells was found to be mediated by proteins in FCS. (C) 2000 Federa tion of European Microbiological Societies. Published by Elsevier Science B .V. All rights reserved.