Monoclonal antibodies VS polyclonal antibodies - Which to choose?

If you’re reading this then hopefully you have an interest for antibodies or you are contemplating which of the two types you ought to use within your research.

To begin, let’s cover a few basics.

Monoclonal antibodies – these singular types of antibody are produced by harvesting purified cell lines derived from a single B cell within the immunity, allowing them to bind to one unique epitope region of an antigen.

On the other hand, polyclonal antibodies describe a collection of antibodies which are grown from different B cells. This makes them capable of recognising multiple epitopes on the same antigen.

Antibodies are used in research as a viable asset to detect target protein/s in procedures like western blotting, immunofluorescence and immunohistochemical analysis. The antibodies are most commonly either monoclonal or polyclonal (although other types exist).

Both types of antibodies are typically created when an antigen, typically for this circumstance, a protein or peptide, is injected into an animal in which its immune system responds to the foreign molecule by producing antibodies specifically targeted against that antigen or precisely to the epitope regions found on that antigen.

When deciding between the use of a monoclonal or polyclonal antibody its worth considering the conditions and aims of your experiment. There are a number of varying factors which differentiate the suitability of using either a monoclonal or polyclonal Antibody. The most significant is the intended use. What are you looking at? What type of protein or peptide do you want your antibodies to bind to?

Below we have covered some of the more distinct advantages and disadvantages presented by each type.

Monoclonal Antibodies

Advantages
- Can produce large quantities of identical antibodies.
- Batch to batch homogeneity.
- Have high specificity to a single epitope which reduces the risks for cross reactivity.
- Better results in assays requiring quantification of the protein levels
- Very efficient in affinity purification

Disadvantages
- Significantly more expensive to produceRequires significantly more time to produce and develop the hybridized clone.
- More demanding storage conditions for the clone.
- 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 labelled.

Polyclonal Antibodies

Advantages
- Inexpensive.
- Quick to produce.
- Ready to use in under four months.
- Easy to store.
- Highly stable and tolerant of pH or buffer changes.
- High affinity as the antibodies bind to more than one epitope, they can help amplify the signal from target protein even with low expression level.

Disadvantages
- High variability between different batches produced in different animals at different times.
- Higher potential for cross reactivity
- The affinity purification of the serum will typically be required to minimize cross reactivity.

The main benefit of monoclonal antibodies is their homogeneity and consistency. The singular specificity provided by monoclonal antibodies is useful in studies focusing on protein-protein interactions, phosphorylation states and in the identification of single members of protein families, e.g. Isomers.

Monoclonal antibodies also enable the study of structural analysis. With their high specificity to single epitopes they can be used to identify if a target proteins demonstrate specific structural features.

However, the specificity of monoclonal antibodies can be considered to be their biggest limitation. Small changes in the structure of an epitope, such as genetic polymorphisms, glycosylation or denaturing of target peptide, can affect the monoclonal antibodies ability to detect and bind to the epitope.

In contrast, polyclonal antibodies are known as heterogeneous because they can recognize a variety of antigenic epitopes, which means any changes on a single or small number of epitopes won’t affect the polyclonal antibody’s ability to detect and bind to the target protein.

Polyclonal antibodies are also more stable over a broad pH and salt concentration, whereas monoclonal antibodies can be highly susceptible to small changes in both experimental conditions.

Therefore, it is safe to state that when selecting which type of antibody to use it’s best to consider what the nature of your experiment is, how much time do you have and what protocols will you be using. As it has been made apparent out of the two types presented, some antibodies are suited for certain conditions better than others.

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