Therapeutic antibodies are man-made substances that are able to bind to specific proteins on the surfaces of cells. Such substances are generally used to treat cancer or autoimmune diseases, though the precise methods of treatment vary significantly. In some cases, the binding specificity of therapeutic antibodies is used to precisely deliver drugs or drug-activating enzymes to precise cellular locations. In other cases, the proteins are used to inhabit binding sites on a given cell, reducing the effects of the overactive immune responses that characterize autoimmune diseases. Many different useful therapeutic antibodies have been synthesized, resulting in a large market for such substances.
Most therapeutic antibodies are monoclonal antibodies, meaning that they are antibodies produced by clones of a single immune cell. Each monoclonal antibody is only able to bind to a single antigen. Both of these properties are highly important when such antibodies are being used for therapeutic purposes. A heterogeneous mix of antibodies that binds to a nonspecific variety of antigens has little therapeutic value as specific binding and precise drug delivery are the two traits that make therapeutic antibodies effective. Monoclonal antibodies can be made to specifically target almost any substance; this capability is highly useful for detection and for targeted drug delivery.
There are many different types of therapeutic antibodies that can be produced in many different ways. Most antibodies are produced within mice and injected into humans in order to fight disease. Rejection, however, is a major problem in antibody production as the human immune system attacks nonhuman antibodies. The human immune system actually produces human anti-mouse antibodies, or HAMAs, in order to confront the perceived threat posed by the mouse antibodies. To deal with this problem, scientists use chimeric antibodies, which are combinations of both human and mouse antibodies, or fully human antibodies, which are produced within the human body to avoid immune response problems.
Many different treatments used for both cancer and autoimmune diseases make use of therapeutic antibodies because of their high level of binding specificity. Some are used to activate drugs at precise cellular locations. Antibodies connected to enzymes bind to specific locations on a cell; the drug is not activated until it makes contact with the enzyme. In other cases, therapeutic antibodies are used to inhabit specific binding sites so that other molecules that could aggravate a given autoimmune disorder are unable to bind to those particular sites. This method is commonly used to combat autoimmune disorders.