Association of Diphtheria Toxin with Vero Cells:Evidence for a Receptor (Diphtheria Toxin/Mammalian Cells/Receptor).

摘要

The interaction of radiolabeled diphtheria toxin with highly sensitive mammalian cell lines was studied. Toxin bound to (or was taken up by) Vero cells at 4 deg and 37 deg in a highly specific manner. At both temperatures, excess unlabeled toxin competed for >90% of the cell-associated label. The association at 37 deg was biphasic, while at 4 deg it followed classical bimolecular reaction kinetics. Both fragment B and CRM-197 blocked the association of labeled toxin with cells. The magnitude of association correlated with the cytotoxic sensitivity of several cell lines. Both pH and exogenous nucleotides affected the association in a manner consistent with effects on cytotoxicity. The label associated with cells at 4 deg was largely intact toxin, while extensive cellular processing of the toxin took place at 37 deg. It is proposed that the toxin-cell association under study represents binding of diphtheria toxin to a biologically relevant receptor.