Pseudomonas toxin has been coupled to monoclonal antibodies to make immunotoxins. When coupled to an antibody to the T cell growth factor receptor to make anti-TAC-PE, it kills leukemia cells that are TAC positive. When injected into monkeys, the immunotoxin has very little toxicity and good survival indicating it may be a useful agent for treatment of this type of leukemia. Adenovirus enters cells in the same vesicles (receptosomes) as these immunotoxins. By lysing receptosomes, adenovirus efficiently releases the immunotoxin into the cytosol and selectively increases cell killing. The penton base of adenovirus is important for vesicle lysis. Adenovirus at pH 5 will permeabilize the plasma membrane of KB cells to small molecules.
