An immunotoxin is a human-made protein which is designed to attack tumor cells. Immunotoxins specifically target tumor cells, leaving healthy cells alone, allowing for a focused attack on a cancerous tumor which may prevent the tumor from spreading or actively shrink the tumor. Hairy cell leukemia is an example of a condition which can be successfully treated with the administration of immunotoxins, and researchers are constantly developing new uses for these specialized proteins.
Immunotoxins are a form of hybrid molecule, blending material from two different proteins which normally are not coupled. Such combinations are said to be chimeric or fusion proteins, reflecting the mix of material from different sources. Scientists use recombinant DNA technology to meld the proteins they wish to include in an immunotoxin, which is why these fusion proteins are sometimes referred to as “recombinant immunotoxins.”
One aspect of an immunotoxin is an antibody, classically a monoclonal antibody produced in mice. A toxin derived from plants or bacteria is attached to the antibody. When the antibody finds a cell it is sensitized to, the cell takes the antibody in, and the toxin is released inside, killing the cell. Immunotoxins exploit endocytosis, a process used by all cells to selectively admit materials through their cell membrane. Like a wolf in sheep's clothing, the immunotoxin tricks the cell into thinking that it is something the cell wants to absorb.
Recombinant immunotoxins have a great deal of potential promise for cancer treatment, because they can target particular cells. Cancer treatment has historically required a very toxic bombardment of the body, in which the hope is that the cancer cells will die during the course of treatment. Along the way, many healthy cells are also damaged, and patients experience complications such as compromised immune systems which can make the recovery process lengthy and unpleasant. With immunotoxins, the patient would not have endure the grueling side effects of cancer treatment.
The challenge with immunotoxin treatment is that the treatment must be designed specifically for the cancer afflicting the patient. The antibodies must be sensitized to particular receptors on the cancer cells, and designed to avoid inadvertently targeting healthy cells in the body. This requires study to determine which kind of cancer the patient has and to find appropriate receptors, followed by patient lab work to create an immunotoxin tailored to the patient's case. Once designed, the immunotoxin can be introduced to the body by injection, so that it can find its way to the cells of concern.
