Enhancement by calcium of the invasiveness of Salmonella for HeLa cell monolayers.

An outer membrane-associated cytotoxin and the invasive capacity of Salmonella were shown to be modulated by divalent cations. Cell detachment activity of salmonella cytotoxin was blocked by addition of either Ca++ or Mg++. It is interesting that Ca++ but not other divalent cations was shown to enhance the invasiveness of Salmonella for HeLa cell monolayers. The dose-dependent Ca++ effect required metabolism and was not simply the result of Ca++ binding to the surface of the bacteria. These data suggest a possible role of divalent cations in the unique relationship of invasive bacteria and host cells.