RT Journal Article SR Electronic(1) A1 Smith, J. A. A1 Cooke, D. L. A1 Hyde, S. A1 Borriello, S. P. A1 Long, R. G.YR 1997 T1 Clostridium difficile toxin A binding to human intestinal epithelial cells JF Journal of Medical Microbiology, VO 46 IS 11 SP 953 OP 958 DO https://doi.org/10.1099/00222615-46-11-953 PB Microbiology Society, SN 1473-5644, AB Clostridium diflcile radiolabelled toxin A ([3H]-toxin A) bound to human duodenal and colonic epithelial cells isolated from endoscopic biopsies. Binding was greater at 4°C than 37°C, consistent with the thermal binding characteristic of toxin A to a carbohydrate moiety. At 37°C colonic cells bound significantly more [3H]-toxin A than duodenal cells. The amount of [3H]-toxin A binding varied considerably between individuals. [3H]-toxin A was displaced by unlabelled toxin A by 50% for duodenal cells and 70% for colonic cells with 94.3 nM unlabelled toxin A. Low non-displacable binding was observed in some samples at 4°C and 37°C, suggesting that these cells came from individuals incapable of specifically binding toxin. Pre-treating cells with α- or β-galactosidases to cleave terminal α- and β-galactose residues reduced [3H]-toxin A binding. There was also a reduction in [3H]-toxin A binding after heat treating cells, which is suggestive of protein binding. The reduction in binding varied between individuals. The reduction of [3H]-toxin A binding, after the removal of β-linked galactose units, implicates these as components of the receptor and adds credence to the idea that the Lewis X, Y and I antigens may be involved in toxin A binding to human intestinal epithelial cells. However, because the Lewis antigens do not possess terminal α-galactose units, the reduction in binding after α-galactosidase treatment suggests that other receptors may be involved in toxin A binding to some human intestinal cells. These data are the first demonstration of direct toxin A binding to human intestinal epithelial cells., UL https://www.microbiologyresearch.org/content/journal/jmm/10.1099/00222615-46-11-953