Jeffrey R. Aeschlimann has a PhD in pharmacy and is an associate professor at the University of Connecticut School of Pharmacy. He has his clinical practice and research work at the UConn Health Center, where he specializes in infectious diseases and oversees the development and implementation of an antimicrobial stewardship program.
Q: Why are antibodies created and how do they form the basis of immunoassays?
Antibodies are created by the body’s immune system in response to an exposure to a foreign (infectious) agent like a bacteria or a virus. These antibodies help to protect the body from damage from future exposures to that specific infectious agent, and are highly specific and bind to specific molecules like proteins, which also makes them very useful for immunoassays.
Q: What are the main steps in the testing process and what are researchers looking for?
The first step in an immunoassay is to develop a screening “toolkit” that consists of the antibody against the molecule of interest — for example, a protein toxin from bacteria — and a “labeled” target molecule. The “label” is usually a substance or an enzyme that allows the researcher to measure the quantity of the target molecule via a color change or by the intensity of fluorescent light emitted. When the antibody-labeled target sample is mixed with a sample that might contain the target molecule (for example, blood from a patient who may have an infection from a bacteria that produces the protein toxin), any additional target molecule can displace the labeled target off of the antibodies, which the researcher can then measure by looking for a change in color or light intensity. The more of the target in the test sample, the more that the labeled target gets displaced, and the stronger the color/light intensity.
Q: What’s a good example of how immunoassays can help researchers better understand disease mechanisms and come up with effective drugs?
One example of how immunoassays have helped us to understand disease is the assay for prostate-specific antigen (PSA), which helps us to screen for, detect, and track the progress of prostate cancer. The results of PSA tests can help researchers and clinicians to determine whether anti-prostate cancer therapy is working, and whether certain types of therapies would be more appropriate than others during the overall treatment course of a patient with this disease. Immunoassays are commonly used to help detect and diagnose a wide variety of infectious diseases. They also can help to diagnose various cancers, track response to therapy, and also are used in other tests such as pregnancy tests and anti-doping tests in competitive sports.
Q: How do immunoassays lead to more precise medical diagnosis?
Since immunoassays rely on antibodies, they are very sensitive and specific. Generally speaking, a well-designed immunoassay will only result in a “positive” test if the molecule of interest is present in the sample that is tested. This means the chances of “false positive tests” are usually quite low.
