12 Making Fusion Toxins to Target Leukemia and Lymphoma

Recombinant toxins are cytotoxic proteins that are encoded by DNA sequences that can be expressed in prokaryotic or eukaryotic cells. The proteins contain both a ligand, for binding to cells, and a toxin, for killing the cells. In recombinant toxins the connection between the toxin and ligand is encoded by the DNA and not produced by chemical conjugation. Since recombinant toxins must bind specifically to cell surface molecules to kill cells, the number of possible recombinant toxin molecules that can bind to a cell is in the hundreds or thousands; hence, the toxins must be very potent.