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Alphabetical Index

Monoclonal & Polyclonal Antibodies

Monoclonal antibodies represent a population of antibodies that recognize a single epitope within an antigen. They are typically produced from a single B cell of an immunized mouse, thereby generating a clonal population of antibodies, identical to one another and all recognizing the same epitope of a specific antigen. Although B cells can be used to harvest antibodies, the disadvantage is these cells have a finite lifespan and will eventually stop producing the antibody. By fusing a specific antibody-producing B cell with a myeloma cell, the limited lifespan of a B cell can be overcome. The resulting immortalized B cell-myeloma hybridoma can provide a constant supply of highly specific monoclonal antibody. Since monoclonal antibodies only recognize one epitope, they generally have low cross reactivity with non-specific antigens. Their epitope specificity, limited cross reactivity, and long term yield make monoclonal antibodies attractive for use in many biological assays and applications.

Polyclonal antibodies represent a population of antibodies collected from multiple B cell clones that have been activated by the immune response of an immunized animal. Traditionally, an animal such as a goat, sheep, or rabbit is injected with a specific antigen that elicits a primary immune response. This is followed by a secondary and tertiary immunization that produces higher titers of antibody against the particular immunizing antigen. The serum containing the antibodies is collected and typically affinity purified in order to enrich for the antibodies raised against the antigen. This process ultimately lends itself to the production of high titer, high affinity polyclonal antibodies against the antigen of interest.

Unlike monoclonal antibodies, polyclonal antibodies cannot be collected for an indefinite amount of time and often require multiple animals to be immunized with the same antigen. Antibodies are harvested from each animal; however, animals immunized with the same antigen develop differential immune responses and this could result in variability in polyclonal antibody production between batch preparations. Since each antibody preparation is collected from multiple B cell clones, polyclonal antibodies represent a heterogeneous population of antibodies that recognize different epitopes within the antigen and bind the antigen with varying affinities. This can prove to be advantageous in many biological assays depending on the particular application. For example, polyclonal antibodies may cross-react with antigens that share high homology, which can be suitable when trying to detect known or unknown isoforms of an antigen. In addition, they can be utilized to enhance the detection level of a particular antigen since multiple antibodies will bind the same antigen at epitope specific regions. This in turn can be valuable when attempting to detect low expressing antigens.

Sigma Life Science offers a large portfolio of monoclonal and polyclonal antibodies. Both monoclonal and polyclonal antibodies can be used in a wide variety of applications including Western blot, immunoprecipitation, immunofluorescence, immunocytochemistry, immunofluorescence, ELISA, and immunohistochemistry. Each antibody is covered by our Bioguarantee, so you can evaluate our antibodies with complete peace of mind.