The polyclonal antibodies are immunoglobulins produced by collections of different lineages of B lymphocytes that recognize the same antigen but react with different epitopes thereof. On the other hand, monoclonal antibodies are produced by a single clone of B lymphocytes, and have a monovalent affinity, that is, they not only recognize the same antigen, but also bind to the same epitope.
Who has not ever wondered if monoclonal or polyclonal antibodies are better? To give an answer to this question, we must first know the differences that exist between them.
DIFFERENCES BETWEEN MONOCLONAL AND POLYCLONAL ANTIBODIES
To analyze the differences between monoclonal and polyclonal antibodies, we will break down the advantages and disadvantages presented by each one.
ADVANTAGES AND DISADVANTAGES OF MONOCLONAL AND POLYCLONAL ANTIBODIES
MONOCLONAL ANTIBODIES (MAb)
- Specificity : By recognizing a single epitope, its specificity is greater, reducing the likelihood of cross-reactions and background noise in the assays.
- Reproducibility : They do not present variability between batches, so if the conditions of a certain test are kept constant, the results are highly reproducible
- Quantity : Hybridomas are immortal cell lines with the capacity to produce unlimited amounts of highly specific monoclonal antibodies.
- Production : the development of hybridomas requires a longer period of time, implying greater cost and the use of more complex technology that requires specialized personnel.
- Intolerance to changes in the antigen : when recognizing a single epitope, in case it suffers some modification by the chemical treatment of the sample, it will stop recognizing the target protein.
- Specificity : the high specificity of monoclonal antibodies can become an inconvenience in those cases in which, for example, it is sought to detect several different proteins but with great homology among them.
POLICLONAL ANTIBODIES (PAb)
- Affinity : to be constituted by a mixture of antibodies that recognize different epitopes of the same protein, they have a high affinity for the antigen, which allows to amplify the signal in the case of proteins with low levels of expression or that are in low amounts in the sample to analyze.
- Tolerance to antigen changes : when recognizing different epitopes, they are much less sensitive than monoclonal antibodies to the small changes that may occur in the target protein as a result of polymorphisms, heterogeneity of glycosylations, denaturation, etc.
- Robustness : due to its ability to bind to different epitopes of the target protein, the results obtained with polyclonal antibodies are usually more robust.
- Production : the production process of polyclonal antibodies is relatively quick and simple, implying a lower cost.
- Reproducibility : by involving the use of different animals for the production of new lots, these can present variability, making the reproducibility of the trials difficult.
- Specificity : as they are not specific, polyclonal antibodies can give rise to cross-reactivity and increase of the background signal.
SO, ARE MONOCLONAL OR POLYCLONAL ANTIBODIES BETTER?
Once the differences between monoclonal and polyclonal antibodies are known , it will be much easier to select the one that best fits our experiment, based on the type of antigen and the application or assay that we have in hand.
For example, for applications that require large volumes of antibodies and require reproducibility between trials, or when we intend to discern between two isoforms of a protein, it is best to opt for a monoclonal antibody.
However, if we work with techniques that require a high affinity, as in the case of immunoprecipitation, or when we have a more limited budget, we could opt for a polyclonal antibody.
The fact that there are differences between monoclonal and polyclonal antibodies does not imply that some have higher quality compared to the others. This will depend on the intended application, the technique in which they will be used, the available budget (in the case of opting for customized production) and the recurrence of their use.