A question that often crops up is - What is the difference between monoclonal and polyclonal antibodies? Good question! Both the way in which these antibodies are produced and what they can be used for, differ greatly.
Here the two types are broken down and all the relevant information about polyclonal and monoclonal antibodies is outlined.
Key differences between Polyclonal and Monoclonal Antibodies.
| Polyclonal |
Monoclonal |
| Heterogeneous population of antibodies with differing paratopes for an antigen |
Homogenous population of a specific antibody with one paratope |
| Not Epitope Specific |
Epitope Specific |
| Increased likelihood for cross-reactivity with similar antigens |
Low cross-reactivity |
| Increased likelihood for background noise |
Low background noise |
| Lot Variability |
Identical lots |
| Inexpensive to develop |
Expensive to develop |
| Quick to produce (approx. 3 months) |
Slow to produce (approx. 6 months) |
| Many host species options |
Few host species options |
What are Monoclonal Antibodies?
Monoclonal Antibodies Definition:
One (mono) type of antibody that binds to a specific epitope on the target antigen makes up a monoclonal antibody.
Monoclonal Antibody Production
To create monoclonal antibodies an immunogen is first injected into a host animal. Once an immune response has been caused by the immunogen, the B-cells from the spleen are extracted and fused with myeloma cells (cancer B-cells).
Healthy spleen cells would not survive indefinitely in cell culture and so this fusing process is carried out to make an immortal cell line. A hybridoma cell line is created through this process.
A mono-culture of B-cells all producing the same specific antibody are created by fusing and culturing single B-cells from the spleen into their own hybridomas.
A specific clone number is assigned to each hybridoma now producing a monoclonal antibody such that the particular antibody and the specific epitope that it binds can be identified.
The B-cells excrete the monoclonal antibodies into the cell culture media. Here, they are extracted for further testing and purification.
The creation of a monoclonal antibody hybridoma clone provides a stable renewable source of antibodies ensuring that each batch is identical to the previous.
In order to create a tumor that secretes a fluid rich in antibodies called ascites fluid, hybridomas may also be injected in the peritoneal cavity of a mouse.
Best Uses of Monoclonal Antibodies:
- To detect a specific antigen
- To detect a single member of a protein family
- To create consistent results between experiments/batches
- To stain cells with less background – excellent for immunohistochemistry, immunocytochemistry, and immunofluorescence experiments
- To quantify protein expression (ex. Flow cytometry or fluorescence-activated cell sorting)
- To detect changes in molecular conformation
- To detect changes in phosphorylation states
- To detect a target for x-ray crystallography
- To create animal models lacking a specific cell type
- Immunotherapy
Monoclonal Antibodies are not Recommended for:
- To detect target proteins across different species based on homology
- To detect low levels of a target proteins
- To detect a protein in an altered conformation
What are Polyclonal Antibodies?
Polyclonal Antibody Definition:
Many (poly) different antibodies that bind to many different epitopes on the target antigen make up polyclonal antibodies.
Polyclonal Antibody Production
An immunogen is injected into a host animal to create polyclonal antibodies. An immune response in the animal is caused by this immunogen activating multiple B-cells, all of which target a specific epitope on the immunogen.
A large number of antibodies with varying paratopes result from this, and therefore varying affinities for the target protein.
After immunization, it is possible to use these polyclonal antibodies straight from the serum (blood with the clotting proteins and red blood cells removed) or alternatively, they can be purified to obtain a solution free from other serum proteins.
New animals will have to be immunized with the antigen to create a new batch meaning that there is a high level of variability from batch to batch.
Best Uses of Polyclonal Antibodies:
- Detecting a known or unknown isoforms of antigens with high antigen homology
- Detecting low levels of a particular antigen
- Capturing as much antigen as possible (ex. Immunoprecipitation or chromatin immunoprecipitation)
- Detecting denatured proteins
- Detecting targets with possible genetic polymorphisms, glycosylation or conformational changes
- Detecting a native protein across multiple assay types
- Detecting a target in solutions with varying pH and salt concentrations
Polyclonal Antibodies are not Recommended for:
- Quantification experiments, for example flow cytometry, as incorrect results will be caused by the amplification of the signal due to the multiple binding sites
- Cases where there are problems with cross-reactivity with high homology proteins
Acknowledgments
Produced from materials originally authored by Leslie Rietveld from StressMarq Biosciences Inc.
About StressMarq Biosciences
Established in 2007, StressMarq Biosciences Inc. is a supplier of life science products that operates out of Victoria, Canada with a small, but dedicated group of scientists. Headed by our CEO and President Dr. Ariel Louwrier, StressMarq provides the research community with high-quality reagents backed with rigorous quality control data, expert scientific support, and fast international delivery.
“Discovery through partnership, Excellence through quality”
With over 7,000 products, our growth can be attributed to the continual production of cutting edge research products. Our diverse portfolio of primary antibodies, antibody conjugates, proteins, immunoassay kits and small molecules bridges across the life sciences, including products for cancer research, cardiovascular disease, cell signaling and neuroscience. To aid research worldwide, StressMarq has an extensive network of international distributors that allow us to supply reagents to over 50 countries.
In the years to come, StressMarq will continue to aid life science research by providing “Discovery through partnership, and Excellence through quality”.
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