The monospecific antibodies are those that specifically recognize a single epitope within an antigen. All monoclonal antibodies, in theory, are monospecific. But what happens to polyclonal antibodies? Can a polyclonal antibody be monospecific? The answer is yes.
In this post we tell you how these monospecific antibodies are obtained, as well as their main characteristics, and we make a comparison against traditional polyclonal and monoclonal antibodies.
Here we go!
MONOSPECIFIC POLYCLONAL ANTIBODIES
Polyclonal antibodies are obtained from the serum of animals immunized with a certain antigen. If the antigen we use for immunization is a specific peptide of our target protein, and once the antiserum has been obtained, we purify it by affinity against that same peptide, the product we obtain is a sample of monospecific antibodies. It’s that simple.
With this procedure, we therefore obtain a reagent that has intermediate characteristics between monoclonal and polyclonal antibodies: on the one hand, monospecific antibodies would maintain the high affinity for the antigen that polyclonal antibodies offer, thus giving robustness to its detection, and on the other, we managed to approximate the characteristics of monoclonal antibodies in terms of specificity , reducing the probability of cross-reactivity and false-positive results.
That is why, in certain cases, monospecific polyclonal antibodies can be an alternative to monoclonal antibodies, if what we are looking for is high specificity, but we have, for example, a limitation in terms of budget or project execution deadlines.
HOW ARE MONOSPECIFIC ANTIBODIES OBTAINED?
The production process of monospecific polyclonal antibodies is very similar to that of the rest of polyclonal ones, with 2 peculiarities:
- Immunization must be carried out with a peptide antigen
- The antiserum must always be subjected to a purification process
The procedure can be summarized in the following stages:
1.- Design and synthesis of the peptide and its conjugation to a carrier protein
2.- Immunization of animals
3.- Collection and titration of the serum
4.- Purification of the antiserum by affinity against the peptide
Although there are commercially available monospecific antibodies against a multitude of antigens, you can also opt for a custom monospecific antibody production service .
MONOCLONAL VS. POLYCLONAL VS. MONOSPECIFIC ANTIBODIES
To conclude, the following table summarizes the main characteristics of each of these antibodies:
| MONOCLONAL | POLYCLONAL | MONOSPECIFIC | |
| affinity | + | +++ | +++ |
| specificity | +++ | + | +++ |
| production time | +++ | + | + |
| cost | +++ | + | + |
| reproducibility between batches | +++ | + | + |