Types of Antibodies
What are polyclonal antibodies?
Polyclonal antibodies represent the antibodies from multiple clones or B lymphocytes, and therefore bind to a number of different epitopes. For antibody production purposes, these are obtained from the serum of an immunized animal, thereby providing a wide range of antibody types and epitope affinities (to molecules other than the intended antigen as well). For many applications, this diversity of antibodies provides an advantage by allowing the researcher to detect multiple epitope sites on the protein of interest. For more information on the polyclonal antibody production services that we offer, please visit our polyclonal antibody page.
What are monoclonal antibodies?
Monoclonal antibodies, by contrast, represent a single B lymphocyte generating antibodies to one specific epitope. Two primary advantages arise with such an application. First, by fusing the lymphocyte with an immortal myeloma cell line (both obtained from mice), one can create a hybridoma cell line capable of producing virtually unlimited quantities of a specific antibody. Second, the antibodies produced are identical and specific only to the epitope of interest. In particular, this is an advantage in applications requiring controlled manufacturing procedures, such as in clinical diagnostic tests or in therapeutic treatments directed towards humans.
Should I use monoclonal antibodies or polyclonal antibodies?
As discussed elsewhere on this site, it is significantly more expensive and time consuming to generate monoclonal antibodies than polyclonal antibodies, and for the vast majority of research applications, they are unnecessary. Polyclonal antibody production can be performed in medium size animals such as rabbits or in large animals such as goats and sheep, allowing anywhere from 200ml to several liters of antibodies to be obtained. For applications requiring greater specificity, affinity purification can be performed, still permitting large yields of high titer antibody to be obtained. For more information on our alternative to monoclonal antibodies, please visit our Monospecific antibodies page.
What are recombinant and phage display antibodies?
The growing popularity of antibodies for use in human therapeutic applications has given rise to technologies that can generate antibodies of human origin. Mouse antibodies, understandably, are seen as foreign by the human immune system, and are therefore either eliminated or prone to complications. Recombinant and phage display technologies have emerged as useful applications for fulfilling these needs. By placing human genes for expressing a particular antibody into a common cell line such as E. coli, researchers can reduce immunogenicity, increase affinity or alter the specificity of the resulting antibody.
With phage display technologies, researchers can go even further by isolating the DNA from human B-lymphocytes, inserting the DNA into E. coli, and then infecting the bacteria with a stringy virus called a filamentous phage. As the phage produce new copies of themselves, they generate the proteins for which the various antibody genes encode. These proteins are then added to the surfaces of new phage. Those phage containing highly specific antibody fragments on their surface can then be isolated from the bacteria by using the antigen target. The selected phage contains the gene of interest, which can then be used to produce larger quantities of the desired antibody in traditional cell culture. While this bypasses the traditional role of immunization, it often fails to acheive high affinities without subsquent processing. Understandably, both of these technologies are expensive and time consuming. However, they do represent significant advances in the development of antibodies as a tool for human therapeutics. For more information on recombinant and phage display antibody production technologies, we recommend visiting The Recombinant Antibody Page or Cambridge Antibody Technology. One other alternative to these technologies is the use of transgenic mice that can produce human antibodies. Medarex and Abgenix are the two most recognized developers of this technology. For additional information on suppliers of various antibodies, please visit the Antibody Resource page.