A comparison between polyclonal and monoclonal

Antibody clonality is determined by whether the antibodies come from different B-cells (producing polyclonal antibodies) or from identical B-cells derived from a parent clone (producing monoclonal antibodies). Then there are recombinant monoclonal antibodies, generated in vitro from a unique set of genes. Polyclonal and monoclonal antibodies each come with their own unique advantages and disadvantages, making them suitable for different applications. 

Summary

• Polyclonal antibodies recognize multiple epitopes on an antigen, are robust, but have high batch-to-batch variability.
• Monoclonal antibodies recognize one epitope on an antigen and deliver a high degree of reproducibility.
• Recombinant monoclonal antibodies have the benefits of monoclonal antibodies, have the lowest levels of batch-to-batch variability, and can have their properties customized through antibody engineering.

Polyclonal antibodies

Polyclonal antibodies are a heterogeneous mix of antibodies, derived from the immune response of multiple B-cells, and each one recognizes a different epitope on the same antigen.

Advantages

• Polyclonal antibodies effectively amplify the signal from a target protein with low expression levels, as the target protein will bind more than one antibody molecule on its multiple epitopes (this is less advantageous for quantification experiments). This makes polyclonal antibodies great for detecting proteins at low concentrations.
• Polyclonal antibodies are more tolerant of minor changes in the antigen (eg polymorphism, heterogeneity of glycosylation, or slight denaturation) than monoclonal antibodies.
• Polyclonal antibodies are robust and more stable over a broader range of pH and buffer compositions than monoclonal antibodies.  
• Polyclonal antibodies can identify proteins with a high degree of homology to the immunogen protein and can be used to screen for the target protein in species other than that of the immunogen (especially useful for looking at non-model organisms).
• Polyclonal antibodies are often the preferred choice for detecting denatured proteins.

Disadvantages

However, recognizing multiple epitopes per antigen means that polyclonal antibodies are

• Prone to a high degree of batch-to-batch variability.
• Likely to cross-react and generate non-specific signal.
• Less useful than a monoclonal antibody for probing specific domains on an antigen.

Monoclonal antibodies

Monoclonal antibodies come from a single B-cell parent clone and therefore only recognize a single epitope per antigen. These B-cells are immortalized by fusion with hybridoma cells, allowing for long-term generation of identical monoclonal antibodies.

Advantages

• Monoclonal antibodies specifically detect a particular or defined/restricted epitope on the antigen, making them less likely to cross-react with other proteins.
• Monoclonal antibodies have a high degree of homogeneity, which means that if experimental conditions are kept constant, results from monoclonal antibodies can be very reproducible between experiments and batches
• Monoclonal antibodies are more suitable for experiments requiring quantification.

Disadvantages

• The epitope target by monoclonal antibodies may not be shared across a range of species, limiting their flexibility.
• Monoclonal antibodies are less suitable for detecting denatured proteins than polyclonals or for use in assays that require antigen cross-linking.
• Monoclonal antibodies are more vulnerable to the loss of epitope through chemical treatment of the antigen than polyclonal antibodies (this can be offset by pooling two or more monoclonal antibodies to the same antigen), - epitope changes can greatly impact binding.
• Monoclonal antibodies are more sensitive to changes in experimental conditions (ie pH and buffer composition) than polyclonals

Recombinant antibodies

Recombinant monoclonal antibodies are developed from a unique set of genes and combine the same properties of monoclonal antibodies with

• Improved consistency and reproducibility
• Ease of scalability
• Animal-free high-throughput production

Read more about recombinant antibodies.