Sirs

Colleagues of the late César Milstein who have read the Landmark article by Sefik Alkan1 are concerned that Georges Köhler's role in the discovery of monoclonal antibodies was over-emphasized. César's colleagues have suggested that I provide some additional information. I am in a good position to comment on the early history of monoclonal antibodies because when César Milstein was a beginner at in vitro cell culture, his tissue-culture laboratory was next to mine, and he turned to me for help and advice2.

In 1970, when César heard that Herve Bazin had developed a rat myeloma cell line in Leuven (Belgium), he asked for the cells so that he could fuse them with his mouse myeloma cells for studying antibody production in a mouse–rat hybridoma. At that time, the only known agent for cell fusion was Sendai virus inactivated with ultraviolet light, which I produced for his studies. After more than two years of continuous effort, Richard Cotton and César managed to generate the first hybridoma that secreted antibody and continuously proliferated while producing antibodies. Their achievement was published in Nature in 1973 (Ref. 3).

Following this successful study, Richard Cotton was offered a prestigious research position in Australia. I continued to produce Sendai virus for César because he wanted to fuse mouse myeloma cells, which he and Richard had made HAT (hypoxanthine, aminopterin and thymidine)-sensitive, with other antibody-producing cells. He was looking for a new postdoctoral researcher to continue with the project and offered it to David Secher. Secher was a research student supervised by César and was about to complete his Ph.D., but Secher wished to continue with his own project. César then asked Georges Köhler to continue the project. Köhler had no experience with cell culture and therefore spent considerable time learning about cell growth in vitro, and again I provided help and advice. In addition, I provided the Sendai-virus preparation that he used, which led to his seminal publication with César4. It was only after Köhler left that César decided to simplify the method for hybridoma formation, and together with Giovanni Galfré, he developed the protocol for hybridoma formation using polyethylene glycol, which became the standard method for generating monoclonal antibodies5.

Alkan states that there was no attempt to patent the method1. There was indeed no attempt to patent it, but it would be wrong to imply that César was to blame. He certainly realized the commercial potential of monoclonal antibodies4, and he did notify the Medical Research Council (MRC) of this before publication. However, in those days, the National Research and Development Corporation were responsible for filing the MRC's patents, and César's information disappeared somewhere in the system.

Alkan's statement that, without Köhler, we might have waited decades to put this together1 is not credible. The entire thrust of César's work was moving in this direction by the time Cotton left his laboratory. Furthermore, after Köhler left, César's laboratory continued to dominate this area of research. Secher was the first to purify interferon-γ using monoclonal antibodies6. César's inspiration and support was also instrumental in the ground-breaking discoveries made by Greg Winter7 and Michael Neuberger8 in the development of new methods for producing humanized and, eventually, human monoclonal antibodies.