Damaging effect of toxic shock syndrome toxin 1 on chick embryo cells in vitro.

The lethal effect of staphylococcal toxic shock syndrome toxin 1 (TSST-1) on rabbits and chick embryos is enhanced in the presence of lipopolysaccharide (LPS). In an investigation of the mode of action of TSST-1, its effect-both singly and in combination with LPS-on tissue culture cell lines was examined. Of a variety of cell lines examined for sensitivity to TSST-1 treatment, only primary chick embryo cells were susceptible. At a critical concentration (0.2 microgram/mL), TSST-1 alone caused detachment of the cell monolayer. In contrast, LPS per se had no visible effect on the cells at any concentration tested. TSST-1 in combination with LPS caused monolayer detachment at all concentrations of TSST-1 employed; thus detachment was independent of TSST-1 concentration in the presence of LPS. The ability of TSST-1 to disrupt the monolayer was neutralized in the presence of polyclonal rabbit antiserum to TSST-1. In a time course study over 24 hours, the effect of the toxin on the cells was initially visible by light microscopy after 4-7 hours. Clear differences in cellular morphology between TSST-1 treated monolayers and untreated controls were observed by scanning electron microscopy. Treated cells lost their normal spindle-shaped appearance before detachment.