The relationship between cytotoxic effect and binding to mammalian cultured cells ofClostridium perfringensenterotoxin

The relationship between the cytotoxic effect and binding to different cell lines of Clostridium perfringens enterotoxin was investigated. The enterotoxin released 51Cr from Vero and MDCK cells labeled with Na2-51CrO4. The effect varied depending upon the dose of enterotoxin and the duration and temperature of the interaction. The enterotoxin gave no effect on FL, KB, or L-929 cells. [125I]Enterotoxin bound specifically to Vero and MDCK cells via a binding site of distinct nature, but not to FL, KB, or L-929 cells. The number of the binding sites located on one MDCK cell (1.98 × 106 sites/cell) was three times that on one Vero cell (5.64 × 105 sites/cell), although the binding affinity of MDCK cell (Ka/ 3.76 × 107 M−1) was 0.1 that of Vero cells (Ka/ 3.23 × 108 M−1). Binding of the enterotoxin to susceptible cells was temperature-independent.