Hi!
does anybody tell me when i can use monoclonal or polyclonal Ab?
Hi! I'll try to answer.
I think it mostly depends on what you want to do with them. Since it recognizes multiple epitopes on the same antigen, a polyclonal antibody has a higher sensibility in detecting and binding the antigen, but it also has a higher probability of binding other molecules non-specifically. In contrast, a monoclonal antibody is manufactured to recognize a single epitope on a specific antigen, meaning it will have a higher specificity for that antigen, but a lower sensitivity, as only one antibody will bind one antigen.
Poly-Abs can be very useful when specificity is not that necessary, since they are easier to obtain and (I guess) cheaper, while mono-Abs are essential for techniques that demand high specificity, like for the detection of protein modifications, for example the phosphorylation state of a tyrosine during a western blot. I'm guessing that if you'd want to, say, detect a common protein like GAPDH, Actin, or as a secondary antibody, you could use poly-Abs, while detecting p-Erk would require a mono-Ab.
Please do correct me if I'm wrong. Have a wonderful evening!
Luca's answer is sound.
To my opinion, there are also other motivations. May try to find them out?
Hi Elisa.
In my notes I also wrote down that for policlonal Ab production you need to purify the antigen, but this can be problematic. First of all, you have to know exactly what the antigen is, and then, it may be difficult to purify it from a cell extract. At the opposite, for monoclonal Ab you don't need to purify the antigen, because the Ab will be selected at a later stage. You might even don't know exactly what the antigen is. For example, if you are looking for an Ab against a specific cell type, it is sufficient to select an Ab that discriminate only that type, but you don't know the antigen recognised, and you can even use an entire tissue for the animal immunisation.
I don't know if my answer was clear, entirely accurate and complete, but I hope it can be useful.
Yes Micol, you perfectly picked the point. In other words sometimes you just don’t have the choice!
Other ideas?
Maybe another point could be the amount of antibodies production. In fact, only small amounts of polyclonal abs can be obtained by injecting an antigen in a single animal, and this will also produce a heterogeneous mixture of which the polyclonal abs of interest will form just a small fraction. By contrast, thanks to the hybridomas approach, which involves immortal cell lines in which the clone of interest can be propagated many times, you can virtually obtain an infinite number of identical monoclonal abs.
Hope my reply to be correct and useful! Have a fine evening everyone :)
Yes. In other words, batches of polyclonal antibodies are finite and you may face variations from one batch to another while monoclonal antibody production is more long lasting and reproducible.