Both Polyclonal and Monoclonal antibodies have their own advantages which make them useful for different applications.
Polyclonal Antibodies
Large quantities of polyclonal antibody are relatively quick and economic to produce compared to monoclonal antibodies. They are non-specific in that they are capable of recognizing multiple epitopes on any one antigen.
Advantages:
Can help to increase the signal produced by the target protein as the antibody will bind to more than one epitope.
More tolerant of minor changes in the antigen, e.g., polymorphism, heterogeneity of glycosylation, or slight denaturation, than monoclonal (homogenous) antibodies.
Useful when the nature of the antigen is unknown.
More robust detection due to multiple epitopes.
Due to recognition of multiple epitopes, polyclonals can give better results in IP / ChIP.
Inexpensive to produce and timeline is short.
Disadvantages:
Prone to batch-to-batch variability.
Multiple epitopes make it important to check immunogen sequence for any cross-reactivity.
Monoclonal Antibodies
Advantages:
Hybridomas provide an immortal cell line with the ability to produce unlimited quantities of highly specific antibodies. Compared to polyclonal antibodies, homogeneity of monoclonal antibodies is very high. If experimental conditions are kept constant, results from monoclonal antibodies will be highly reproducible between experiments.
All batches will be identical and specific to just one epitope, which is a particular advantage when manufacturing procedures must be standardized e.g. clinical tests and therapeutic treatments.
The high specificity of monoclonal antibodies decreases background noise and cross-reactivity, which helps provide reproducible results, and ensures efficiency in affinity purification.
Specific antibody characteristics can be identified and selected. For example, sensitivity requirements and cross-reactivity levels can be specified and monoclonal antibodies screened to identify any cell lines exhibiting the required characteristics.
Disadvantages:
Antibodies may be too specific (e.g. less likely to detect across a range of species)
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.
Expensive to produce and timeline is long for hybridomas.