Multiclonal Antibodies

Multiclonal antibodies, also known as oligoclonals, are cocktails of monoclonal antibodies that can offer several advantages for scientific research. To understand how they are produced, it is worth recapping how conventional monoclonal and polyclonal antibodies are generated and the benefits they can bring to common immunoassay techniques such as Enzyme-Linked Immunosorbent Assay (ELISA), Immunoprecipitation (IP), Western Blotting (WB), and Immunohistochemistry (IHC). In either a polyclonal or monoclonal setting, antibody development is initiated by immunizing an animal with the protein target of interest. This is then recognized by circulating B lymphocytes via the unique antibody displayed on the surface of each B cell. Upon binding to its specific antigen, a B lymphocyte undergoes clonal expansion to form a pool of identical plasma cells that all express the same antibody. At this stage, the animal serum may be used directly, or the antibody may be purified using Protein A, Protein G, or the immobilized antigen. Such antibody preparations are said to be polyclonal since they are the product of multiple B cell clones. Monoclonal antibody production is more complex. Instead of harvesting the serum, the spleen is removed from the animal and the B lymphocytes are isolated for fusion with immortal myeloma cells. The fusion process generates hybridomas, which are then plated out via the limiting dilution method and established in culture, where they secrete antibodies into the growth medium. By using an ELISA to screen the secreted antibodies, it is possible to identify the best-performing clones for in vitro expansion. An advantage of polyclonal antibodies is that they can improve assay sensitivity as a result of being able to bind multiple epitopes. This can be especially useful when detecting scarce targets, or proteins that are likely to change conformation, as well as when performing techniques like IHC and IP, in which certain epitopes may become masked by fixation, crosslinking, or the formation of protein complexes. Advantages of monoclonal antibodies include their high specificity, consistent experimental performance, and availability in unlimited long-term supply. Mutliclonal antibodies combine the benefits of both polyclonal and monoclonal antibodies in a single preparation. They are produced by mixing several monoclonal antibodies together in an optimized ratio and are seeing increased use for many different research applications. Mutliclonal antibodies typically consist of several labeled or unlabeled mouse monoclonal antibodies or rabbit monoclonal antibodies. In addition, mutliclonal antibodies are of interest for their therapeutic potential. Examples to have received regulatory approval include the paired HER2-targeted monoclonal antibodies trastuzumab and pertuzumab for treating breast cancer and the combination of ipilimumab and nivolumab for treating melanoma.