FIG. 2.

Representative photomicrographs (viewed at ×200 magnification) of T84 cells in the presence or absence of purified large clostridial toxins TcdA and TcdB, antibodies directed against TcdA (Anti-A) and TcdB (Anti-B), tolevamer, or C. difficile culture supernatant (Sup). Studies were repeated three times. Top panels, controls showing the absence or presence of antibodies to TcdA or TcdB alone in the absence of toxin; middle panels, C. difficile culture supernatant plus antibodies alone or in combination; bottom panels, purified TcdA and TcdB alone and C. difficile culture supernatant plus tolevamer. These panels illustrate the results of using C. difficile culture supernatant from strain VL00013; the results with other BI/027 supernatants were similar. The results from using tolevamer to neutralize purified TcdA and TcdB were similar to those for the C. difficile culture supernatant (data not shown).