Animal derived antisera always contain many unwanted Immunglobulins of unknown specificity, causing an intrinsic risk of unwanted reactivities which can never be completely excluded by affinity purification steps2-7.
While also still depending on animal immunization, the hybridoma technology substantially improved this scenario, as it allowed the production of monoclonal antibodies for the first time.
Yet, contrary to widespread belief, these antibodies are not always monospecific. As shown in a multicentric study8 of 185 monoclonal hybridoma sequences, a striking 30 % of these hybridomas expressed additional productive light chains, sometimes even additional heavy chains, resulting in the generation of an oligospecific mixture of antibodies in their supernatant.
So, hybridoma-derived monoclonals are not always as defined as we thought. Furthermore, hybridoma antibodies do not provide the epitope diversity of polyclonals, which can result in lower signals and a more narrow application profile. Finally, storage of hybridoma lines in liquid nitrogen constitutes a quite expensive and not flawless system, that already caused the loss of countless hybridoma clones, making a future reproduction of results with these antibodies impossible.
As a result, the only unequivocally monoclonal antibodies are sequence defined antibodies generated and produced with recombinant technologies, most prominently antibody phage display. Only these antibodies provide infinite reproducibility, since they can always be reconstituted from their electronically stored or printed amino acid sequence.