PROTECTION OF MAMMALIAN-CELLS FROM DIPHTHERIA-TOXIN BY EXOGENOUS NUCLEOTIDES

Exogenous nucleotides protected mammalian cells from the lethal effects of diphtheria toxin. Protective potency of a given nucleotide was base specific and phosphate chain length dependent. Full expression of protective potency required an intact nucleotide, but the effect did not appear to be mediated by nucleotide-induced phosphorylation. Nucleotides antagonized the binding of diphtheria toxin to its cell surface receptor in a manner that correlated with the degree of protection. Cellular protection from diphtheria toxin by nucleotides apparently results from inhibition of toxin-receptor binding and nucleotides therefore may serve as valuable research tools for future studies.