We all know it from biology lessons at school: Antibodies help us to ward off disease and are essential components of our immune system. What many people do not know is that physicians and scientists use animal antibodies to identify diseased or mutated cells. This makes them an important instrument in the diagnosis of diseases such as cancer.
Secondary antibodies binding primary antibodies. The result is visible under a microscope.
The key of immunohistology: The binding feature
Antibodies are formed in certain blood cells in answer to substances that the immune system classifies as harmful. These so-called antigens are molecules that are located, for example, on the surface of viruses or bacteria. Again, the antibodies bind certain areas of the antigens called epitopes. This way they signal the immune system to reduce these foreign binding structures.
This binding character is also useful in diagnostics: In the immunohistology or immunohistochemistry procedures there are antibodies inserted to make certain structures, such as proteins, visible. “These procedures have been used since the late 70’s and have been continuously improved and expanded,” explains Jürgen Frerichs, head of DIANOVA GmbH, one of the established commercial enterprises in the sector.
Targeted synthesizing of antibodies
To put it simply, biotech companies and research institutions produce antibodies by injecting one specific antigen into a mouse, a goat or a horse. The ensuing immune reaction stimulates the body to create a great amount of antibodies with several binding features for the antigen. It is then possible to isolate the antibodies directly from the blood, or even isolate particular antibody-producing blood cells from the mixture extracted from certain animals and initiate a complex biotechnological procedure for the production of an excess of a single antibody. Antibodies that are produced like this are called “monoclonal”—they emanate from one single cell line and bind just one particular epitope.
Antibodies are very small and even under a microscope not readily visible, which is why they are specially prepared for the diagnostics. They are coupled with enzymes that produce visible colorants or are marked with fluorescing colorants. There are two methods: The direct and the indirect technique. The latter works with an added bridge that consists of another antibody (secondary antibody) that binds the first one (primary antibody).
Antibodies help to distinguish tumor cells from each other
One example is the anti-IDH1 R132H monoclonal antibody clone H09 of DIANOVA GmbH, by which different brain tumors can be distinguished from each other. Originally developed by the renowned German Cancer Research Center, the antibody labels gliomas, which account for about 20 percent of all brain tumors. Differentiating gliomas from other brain tumors enables to launch a targeted treatment and helps predict the course of the disease.
Multiple advantages in contrast to gene sequencing
The use of antibodies in diagnostics provides many advantages in comparison to molecular-biological methods, especially in the diagnosis of brain tumors, when there is often less tissue available. In addition, the percentage of tumor cells in the tissue sample is a critical factor. Immunohistochemistry is faster and cheaper than gene sequencing procedures.
"Another advantage of the immunohistochemical method with antibodies is that pathologists have the result right in front of their eyes—they can differentiate diseased from healthy cells under the microscope," said Frerichs.