Polyclonal antibodies

Polyclonal antibodies are a collection of immunoglobulin molecules that are secreted against a specific antigen, each recognizing a different epitope.

Overview

A single antigen may contain several different epitopes, each capable of provoking a different immune response. When a mixture of antibody molecules react to different epitopes, they are said to be polyclonal. Polyclonal antibodies are used in a variety of diagnostic and therapeutic applications.

Production

Polyclonal antibodies are typically produced by immunizing an animal, such as a rabbit or a goat, with an antigen. The animal's immune system responds to the antigen by producing a mixture of antibodies, each of which recognizes a different epitope on the antigen. The serum containing these antibodies is collected and purified to obtain the polyclonal antibodies.

Applications

Polyclonal antibodies are used in a variety of applications, including:

• Immunohistochemistry: Polyclonal antibodies are often used in immunohistochemistry, which involves staining tissues to detect the presence of certain antigens. Because they recognize multiple epitopes, polyclonal antibodies can bind to more antigens and provide a stronger signal.

• Western blot: In Western blotting, polyclonal antibodies are used to detect proteins that have been separated by gel electrophoresis and transferred to a membrane.

• Enzyme-linked immunosorbent assay (ELISA): Polyclonal antibodies are used in ELISA to detect the presence of an antigen in a sample.

Advantages and Disadvantages

Polyclonal antibodies have several advantages over monoclonal antibodies. They are easier and less expensive to produce, and because they recognize multiple epitopes, they are less likely to be affected by minor changes in the antigen. However, they also have some disadvantages. The composition of a polyclonal antibody preparation can vary from batch to batch, making it difficult to obtain consistent results. In addition, because they recognize multiple epitopes, they may cross-react with other antigens and cause nonspecific binding.

See Also

• Monoclonal antibodies
• Antigen
• Epitope
• Immunoglobulin