What is a Polyclonal Antibody?
A Polyclonal Antibody represents a collection of antibodies from different B cells that recognize multiple epitopes on the same antigen. Each of these individual antibodies recognizes a unique epitope that is located on that antigen.
- Inexpensive to produce.
- Quick to produce. Purified antibody ready to use in under four months.
- Easy to store.
- Highly stable and tolerant of pH or buffer changes.
- Higher overall antibody affinity against the antigen due to recognition of multiple epitopes.
- In general, ability to detect multiple epitopes gives more robust detection.
- Offers greater sensitivity for detecting proteins that are present in low quantities in a sample since multiple antibodies will bind to multiple epitopes on the protein.
- Ideal as the capture antibody in a Sandwich ELISA. Greater ability to quickly capture the target protein.
- Superior antibody affinity generally results in quicker binding to target antigen. Ideal in assays requiring quick capture of the protein such as IP or ChIP.
- Significantly more robust when assaying proteins that show slight variations in individual epitopes such as denaturation, polymorphism or conformational changes.
- Superior for use in detecting a native protein in multiple assay types.
- Much easier to couple with antibody labels. Less likely to affect binding capability.
- Variability between different batches produced in different animals at different times
- Higher potential for cross reactivity due to recognizing multiple epitopes
- Affinity purification of the serum will typically be required to minimize cross reactivity
What is a Monoclonal Antibody?
A Monoclonal antibody, by contrast, represents antibody from a single antibody producing B cell and therefore only binds with one unique epitope. Each individual antibody in a polyclonal mixture is technically a monoclonal antibody; however, this term generally refers to a process by which the actual B-cell is isolated and fused to an immortal hybridoma cell line so that large quantities of identical antibody can be generated.
- Can produce large quantities of identical antibody. Batch to batch homogeneity.
- High specificity to a single epitope. Reduced probability of cross reactivity.
- Can provide better results in assays requiring quantification of the protein levels.
- Significantly more expensive to produce.
- Requires significantly more time to produce and develop the hybridized clone.
- Small changes in the epitope’s structure often render the monoclonal antibody unable to detect the target protein.
- More demanding storage conditions for the clone.
- Cell culture and purification capabilities required.
- Less robust for detecting the protein in a denatured state or altered conformation.
- Less ideal for application requiring quick capture of the target protein.
- More sensitive to pH and buffer conditions.
- More susceptible to binding changes when labeled.
- To offset many of these disadvantages, it is necessary to produce a pool of several monoclonal antibodies. This is typically cost and time prohibitive.
For applications such as diagnostic manufacturing and therapeutic drug development that require large volumes of identical antibody specific to a single epitope, monoclonal antibodies can be an ideal solution. For general research applications, however, the advantages of polyclonal antibodies typically outweigh the few advantages that monoclonal antibodies provide. With affinity purification of serum against small antigen targets, the advantages of polyclonal antibodies are further extended. Monospecific antibodies, discussed in the next section, offer what we feel is the best of both worlds by combining high antibody specificity with low cost and rapid production.
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