Proteintech

A brief history of the antibody – part II, monoclonal antibodies

By Deborah Grainger

As promised in part I of this series, I have posted two more installments of “a brief history of the antibody”, imaginatively named, “a brief history of the antibody – parts II and III”.  However, unlike the last post – which could stand alone independently – these latest installments have been written together and I recommend reading both in relative succession. They narrate the history behind the discovery of monoclonal antibodies (or at least my interpretation of it) and have, therefore, been unified by the subtitle of “monoclonal antibodies”.

I am going to be honest, I struggled with this one at first – largely because it feels like I am trying to teach fish how to swim – most life scientists know how monoclonal antibodies were developed; or at least, I assume – I remember covering it in the first or second year of my undergraduate degree. However, if I had been faced with writing this article at that time, I imagine it would have gone thus: “two blokes figured out how to add a B-cell to another immortal type of cell and the resulting cell line divided indefinitely, producing identical antibodies until further notice. People decided this was useful and began making lots of different but identical antibodies for the benefit of the scientific and medical world. The end. ” – It would have been a bit of an over-simplification to say the least.

César Milstein

“A very simple experiment” 

Like the majority of advancements in science, the story of monoclonal antibodies is not as clear cut as my undergraduate-self would have told it. In the history books of science, discoveries and breakthroughs are almost always a result of several events and smaller breakthroughs, carried out by a number of individuals – and the engineering of the monoclonal antibody was no exception. In his Nobel lecture, delivered on 8^th December 1984, César Milstein – one of the main protagonists in the monoclonal breakthrough and one of the “two blokes” referred to in my introduction – mentions over 30 contributing individuals by name. As well as delivering an interesting scientific account of his work and the people in it, his speech tells a story that begins in 1962 in Argentina with his early research. However, it was not until the early 1970s, some 10 years after moving to the MRC labs in Cambridge, that the idea of creating antibody producing cell lines began to take shape. The years in between were not spent waiting idly (I’d imagine no scientist ever gets a Nobel Prize that way), but pursuing Milstein’s original research aim: uncovering the nature of antibody diversity. Milstein states this is what attracted him to immunology in the first place, “the whole thing seemed to revolve around a very simple experiment: take two different antibody molecules and compare their primary sequences. The secret of antibody diversity would emerge from that”. He then adds: “Fortunately at the time I was sufficiently ignorant of the subject not to realize how naïve I was being.” [1]

Scratching the surface

The Nobel Prize in physiology or medicine, awarded for the development of monoclonal antibodies, was not only awarded to César Milstein and his collaborator Georges Köhler, but also to a scientist named Niels K. Jerne. Jerne is not mentioned as often as Milstein and Köhler as he was not directly involved in the laboratory work, but was a key immunologist at the time who had discovered much of the theory enabling the latter two scientists to make their breakthrough. In his Nobel talk, Jerne unintentionally alluded to the naïvety of Milstein’s initial idea of immunology. In the opening of the lecture [2], he highlighted how the human immune system is made up of around 10¹² lymphocytes, divided almost equally into T cells and antibody secreting B cells, and that any one of the 10⁶ B cells in the body is capable of producing many copies of one single type of antibody. A typical response to a foreign antigen is characterized by the polyclonal production of many hundreds of different antibodies: it involves several hundred individual B cells, or rather B cell clones, which become stimulated to divide and mature into antibody producing cells – each capable of excreting around 2000 antibody molecules per second [2]. Characterizing the diversity of two different antibodies out of these millions of individual B cells would only begin to scratch the surface.

Early work

Over the years, Milstein took several approaches in his research concerning the diversity of antibodies. His first experiments consisted of digesting purified and iodinated antibodies, generated by different antigens, and separating the products; the patterns that emerged were too complex and similar and from this he concluded that the protein chemistry of antibody diversity differed too subtly to be determined at that time. A different approach was required and Milstein, along with George Brownlee, attempted to isolate antibody mRNA, particularly any coding for the light chains. Back then there was no DNA sequencing, only mRNA sequencing via elaborate fingerprints of radioactive mRNA. This work led to the separate discoveries that an extra N-terminal sequence signals immunoglobulin transport across membranes and that the V- and C-regions are made from a single mRNA strand and are integrated before protein synthesis.

Georges Köhler joins Milstein in Cambridge

Georges Köhler

Milstein identifies the advent of tissue culture in his lab as having a major impact on the direction of its research. Using tissue culture techniques, his lab first began to look at the rate of somatic mutations in P3 myeloma cells (cancerous effector B/plasma cells). They found that the rate at which these mutations occurred suggested an important role for somatic mutation in the generation of antibody diversity; however, no mutations were found in the variable region which forced Milstein and colleagues to conclude that the antibody made by the P3 cells may lack the hypervariable segment – “In a sense we were back to square one”. However, it was this group of results that César Milstein took to the Institute for Immunology in Basel to deliver a seminar. Present in the audience was Georges Köhler, the researcher who would have the initial idea to produce an antibody secreting cell line in-house. He was ready to submit his PhD thesis and looking for a postdoctoral position, also fascinated by the nature and origin of antibody diversity. At Basel, Milstein invited Köhler to join him at the MRC labs in Cambridge and Köhler accepted. It was a collaboration that was to prove, in the grand scheme of things, very successful indeed. If I was not so engrossed in the subject, I could have signed off here with a “and the rest is history”, but the story just keeps on getting interesting; part III has the rest of my narrative…

References and resources:

 [1] César Milstein, Nobel lecture: ”From the structure of antibodies to the diversification of the immune response”, 8 December 1984 (www.nobelprize.org).

[2] Niels K. Jerne, Nobel lecture: “The generative grammar of the immune system”, 8 December 1984 (www.nobelprize.org).

Other related resources:

Georges Köhler, Nobel lecture “Derivation and diversification of monoclonal antibodies”  8 December 1984 (www.nobelprize.org).