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Antibodies

Antibody 101: Monoclonal Vs Polyclonal

What is an antibody?

An antibody (Ab) or immunoglobulin (Ig) is a protein produced by the immune system to identify and neutralize foreign objects including bacteria, fungi, viruses, and toxins. These large, Y-shaped proteins are composed of two heavy chains and two light chains held together by disulfide bonds. The tip of its Y-shaped structure contains a paratope which can recognise and bind with a specific epitope on a corresponding antigen, rather like a lock and key. Once bound, the antibody can either neutralize the antigen by blocking a part of the virus that is essential for it to invade cells or tag it for attack and removal by other parts of the immune system.

Antibodies have high selectivity and specificity and as a result, they are used extensively in molecular biology, from basic research to diagnostic tests and therapeutics. There are two main types of antibodies used in research: monoclonal and polyclonal. Monoclonal antibodies recognize a single antigen and bind with one epitope. Polyclonal antibodies also recognize a single antigen, but they can bind with multiple different epitopes.

An antibody is made up of two light chains and two heavy chains held together by disulfide bonds. The antigen binding site or paratope is antigen-specific. (Image by OpenStax College, Wikimedia commons).

Monoclonal Antibodies

Monoclonal antibodies are immunoglobulins that high have specificity towards a specific antigen or epitope. One of the most common methods used to produce monoclonal antibodies is the use of hybridoma technology. In this process, B lymphocytes are isolated from an animal that has been inoculated with a specific antigen and fused with myeloma cell lines to form hybridoma cell lines. These hybrid cells are immortal and can be used to produce a population of identical cells that contain the same type of antibody.

Monoclonal antibodies can also be produced using a variety of recombinant systems including mammalian, microbial, and insect cells. In this process, antibodies are generated in vitro using synthetic genes, removing the need for animals. Briefly, this involves cloning antibody-coding genes into an appropriate phage vector and introducing this vector into a host cell to achieve expression of the functional antibody.

Monoclonal antibodies are used extensively in research laboratories around the globe and are an invaluable tool for molecular and biomedical research. Applications include diagnosis of diseases, protein purification, hormone tests, therapeutics, preparation of vaccines, and examining the structure of cell membranes to name but a few.

Monoclonal antibodies are produced by fusing B lymphocytes from an inoculated animal with myeloma cells (Diagram via Adenosine, Wikimedia commons).

Polyclonal Antibodies

Polyclonal antibodies are a heterogeneous mix of antibodies that targets various epitopes on the same antigen. They are generated by injecting an animal, such as a rabbit or a chicken, with an immunogen along with an adjuvant to stimulate the immune response. The animal is then injected again about a month later and every 2 – 3 weeks after until the desired level of antibodies is reached. This is checked by testing the antibody titer after each immunization. The whole process can take from 2 to 4 months.

Once the desired level of antibodies is reached, blood is taken from the animal and separated. The serum is then collected, and the antibodies are isolated from it. One advantage of using polyclonal antibodies is that they are inexpensive compared to monoclonal antibodies and can be produced within a relatively short time. They can also be purified relatively simply by using methods such as high-affinity chromatography. On the downside, these antibodies have a higher chance of cross-reactivity. The antibody response also depends on the host animal and so can vary considerably between batches.

Polyclonal antibodies are used widely in diagnostic assays due to their ability to recognize the different epitopes of a target molecule, and as a secondary antibody in immunoassays such as ELISA, western blotting, immunohistochemistry, and flow cytometry. Their ability to bind to different epitopes enables them to amplify the signal, resulting in better detection.

How Can We Help?

Cepham Life Sciences offer a wide range of quality antibodies that are manufactured using identical immune cells that are all clones of a unique parent cell. Our antibodies all have monovalent affinity, making them ideal for both research and diagnostic purposes. For more information have a look at our website or contact one of our team who will be happy to answer all your questions.

Contact Cepham Life Sciences Today!

Cepham Life Sciences team is available to meet all your proteomics and molecular biology laboratory needs. We have a wide range of quality research products, and our team of experts are on hand to offer advice and answer any questions that you have. You can reach us by phone at (410) 636-4954 or Toll-Free at 1-800-257-1565 (USA/CANADA) or by email.

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