Antibody Detection Methods

When doctors and researchers are investigating a disease, one important factor they must identify is antibodies. The presence of antibodies in the blood stream or in a dish of cells in a laboratory signifies a response to foreign invaders such as bacteria or virus particles. Several ways exist to screen for antibodies, all of which require sophisticated equipment.

Staining and Dying

• Perhaps the simplest way to identify antibodies on cells is by looking at them under a microscope. Biological research companies have created dyes and stains that specifically mark a targeted antibody. Once the researcher has applied a dye to the cells, she can look at the sample with a microscope. The antibodies stand out against the background of other cellular components thanks to the dye.

Enzyme-Linked Immunosorbent Assay

• Enzyme-linked immunosorbent assay, or ELISA, is another way to identify antibodies. During this technique, a scientist is typically looking for a specific antibody in a sample. He purchases a commercially produced antigen, a protein that explicitly binds to a specific antibody. Once he adds the sample to the antigen solution, he looks for enzymes that signal binding of the antigen, which suggests that the antibody in question must be in the sample.

Immunoprecipitation

• Immunoprecipitation works much in the same way as ELISA. A scientist takes a sample, either of a patient's blood or a dish of cells grown for experiments, and exposes it to an antigen. Then she adds another item, a protein that protects the antibody connected to the antigen from dissolving in liquid, such as water. She then washes the entire sample. After the washing, only the antibody-antigen complex remains.