Immune system is complex set of cells, chemical signals and proteins united to target and eliminate the antigens (foreign molecules) after they enter the body. Antigens could be infective agents (like microorganisms), toxins or endogenous metabolites that should be cleared from the body. B-lymphocytes produce specifically shaped immunoglobulins (class of proteins) better known as antibodies that will bind to antigens and remove them from the organism. Bond between antigen and antibody is strong and specific: perfectly designed antibody will match antigen just like key will match certain lock. When organism is facing disease for the first time, it needs time before adequate antibody is created, but with each new infection (caused by the same pathogen) - immune response will be executed faster. Vaccination is mimicking naturally occurring pathogen attack; provoked immune system will produce antibodies against the pathogen and provide resistance against specific disease. A lot of severe infectious diseases were eradicated thanks to vaccination.
Besides vaccination, advanced technological methods allowed scientists to produce desired antibodies in laboratory using different animal species (by purifying their blood or through cellular cloning). Until recently, antibody production was exclusively associated with living creatures. Basic structure of the antibody is well known, but there is still a variable part of the protein that will change to fit each new antigen presented. In the body, one B cell lymphocyte could produce over billion different antibodies that will match and eliminate foreign substances successfully. Manually created antibodies were hard to produce without modern manufacturing techniques. Nanotechnology is already widely used and applied in various scientific fields. It proved to be useful even in the field of immunity, enabling scientists to develop first plastic antibody.
Dr. Ken Shea, Professor of the Chemistry at the University of California, designed and tested first nanotech derived antibody. Nanomaterials and nanoparticles are made out of polymers that will assemble in a predetermined way. To obtain a mold that will be used for the artificial antibody production, plastic material was placed around antigen. After antigen was removed, cavity that left behind served as pattern for plastic antibody production because it perfectly matches shape of the antigen that should be recognized and eliminated. When bigger pool of plastic antibodies was created, professor Shea start experiments with mice to test their efficacy in vivo. Mice were injected with lethal dose of bee venom. Animals that didn't receive plastic antibodies died, while 60% of immunized mice survived lethal dose of toxin. Important observation in this experiment was that plastic antibody managed to recognize circulating toxin (antigen) out of many other molecules in the blood and successfully eliminate it in 60% of animals. Besides proven selectivity, plastic antibodies have few more advantages compared to naturally derived antibodies. They are abiotic and manufacturing process doesn't require living organisms. Production is simple, faster and cheaper than conventionally applied procedure. Artificial molding of the antigen requires less time than naturally occurring recognition and response. Also, plastic antibodies could be applied in numerous ways. Dr. Shea’s laboratory is mainly focused on antidote production. Intoxication after snake or spider bite are often in the nature; some of them require fast and efficient treatment, and unfortunately, list of toxins without appropriate antidote is still long. Other promising application of plastic antibodies could be seen in protein purification and in a diagnostics field. Couple of issues needs to be solved before experiments on human start. Scientists still investigate clearance and metabolism (after binding to the antigens) of plastic antibodies. Main weak point: without naturally created antibodies, organisms will not “remember” antigen attack and it will be helpless when same antigen enters the body in the future (if artificially antibodies are not provided again). As mentioned before, adequate immune system response is dependent upon chemical signals and different type of cells that are playing complex roles while defending the body against foreign substances. Plastic antibodies couldn't communicate with the rest of the immune system and couldn't blend in cascade events typical for the immune response - they act on their own. But that doesn't mean that artificial antibodies should be rejected, they just need to be modified.
Plastic antibodies proved to have great potential and multiple applications and it is just a matter of time when they will be improved and approved for human use.