Interaction between clostridium difficile toxin a and mammalian cells

The interaction between Clostridium difficile toxin A and human cells was studied using both WI-38 cells and red cell ghosts. The adsorption to cultured cells was rapid during the first 10 min of exposure. There was a late increase in adsorption at higher temp. Toxin binding to the RBC ceIJ ghost was temperature-dependent; higher at 370 than at 22o or O oC. The adsorption to both WI-38 cells and to RBC ghost was not influenced by pH changes ranging from 6.4 t0 7.8. The release of bound toxin from WI-38 cells was minimal from intact cells. but greatly accelerated after the cells had been broken by repeated freezing and thawing. The release of toxin from the RBC cell ghost was not detected until 28 h after incubation, regardless of the incubation temp. Only ghosts of human RBC were shown to bind toxin. RBC ghosts were inactivated in toxin binding in: thesus monkey, dog, rabbit, sheep, rat. hamster. guinea pig and chicken. Treatment with either 2-mercaptoethanol or N-ethyl maleimide caused inactivation of toxin which was not reversible after its removal, suggesting that disulfide and sulfhydryl bonds are essential for toxicity.