Immunotoxins--entry into cells and mechanisms of action.

Immunotoxins, that is conjugates of enzymatically active toxins with antibodies against cell surface antigens, are being used in targeted cell destruction. The directed toxin enters the cytosol of the target cells and inactivates components of the protein synthesis machinery. In this review, Sjur Olsnes, Kirsten Sandvig, Ole W. Petersen and Bo van Deurs discuss the mechanism of action of such conjugates and how they enter the cytosol. Emphasis is placed on points that should be considered in the preparation of efficient conjugates.