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Albert Coons: harnessing the power of the antibody

2016; Elsevier BV; Volume: 4; Issue: 3 Linguagem: Inglês

10.1016/s2213-2600(16)00020-5

2213-2619

Greer Arthur,

Historical Medical Research and Treatments

American physician, immunologist and pathologist, and the pioneer of antibody labelling and immunofluorescence. Born in Gloversville, USA, in 1912, he died on Sept 30, 1978, aged 66 years. The powerful principle of immunostaining, which harnesses an antibody's innate immunological properties to recognise specific biological targets, has affected clinical research since as early as 1941. In that year, Albert Hewett Coons and colleagues from Harvard University reported that they were able to use fluorescently labelled antibodies to visualise pneumococcal antigens in infected tissue specimens. The results were hailed as a milestone achievement, and since then the technique has been interminably improved, adapted, and enhanced upon to produce an indisputably invaluable and versatile method for both diagnostic and research laboratories. Improvements and developments continue even now, and to such an extent that immunohistochemistry has now entered the age of automation; a remarkable feat in view of the complexity of human tissue and the heterogeneous nature of most diseases. Furthermore, subcellular localisation and resolution are now routinely achieved. But, despite the advances achieved in the past 70 years, the underlying principle developed by Coons remains remarkably unchanged. Albert Coons was born in Gloversville, New York, USA, on June 28, 1912, to Albert Selmser and Marion (Hewett) Coons. Following an education in Gloversville public schools, Coons attended Williams College in 1933 and then studied medicine at Harvard Medical School, from which he graduated with an MD degree in 1937. Coons' interest in research and immunology reportedly stem from his time studying medicine, during which he undertook an immunology course led by Hans Zinsser, a professor of bacteriology and immunology at Harvard Medical School between 1925 and 1940. This course apparently impelled Coons to embark on a laboratory-based research project with an assistant professor, John Enders, in 1935. The project, which studied levels of antibodies in blood and their role in anaphylactic sensitisation in animal models, provided Coons with an immediate introduction to the immunological potential of antibodies. At this point, although antibodies had already been identified as proteins by Oswald Avery and Michael Heidelberger of the Rockefeller Institute in the 1920s, the chemical structure of antibodies was unknown. Precipitation reaction experiments done as early as 1890 by Kitasato Shibasaburō, a Japanese physician and bacteriologist, showed that immune serum could bind to and cause aggregation of proteins within solutions. Precisely how the antibody was able to induce precipitation of an antigen in solution, however, had yet to be elucidated. Previously, in 1897, Paul Ehrlich, a German physician credited with the first use of the term antibody, postulated that a lock-and-key mechanism of antibody–antigen binding existed. A few years later, in 1904, Almroth Wright, a British immunologist and bacteriologist, suggested that antibodies could coat foreign antigens and thus label them for phagocytosis—a process now referred to as opsonisation. By 1935, attempts to prove the mechanism of precipitation were still ongoing, with studies examining the theory that antigen and antibody interactions either triggered a physical change in the sample, or were the result of a direct compatibility between the molecular structure of the antibody and its target antigen. After receiving his MD from Harvard, Coons worked as a house officer at Massachusetts General Hospital for 2 years until 1939, at which point he became an assistant resident at Thorndike Memorial Laboratory at Boston City Hospital for another year. In 1940, Coons started a research fellowship at Harvard in the Department of Bacteriology and Immunology. Despite the relatively basic knowledge of antibodies at this time, Coons began to develop a concept of visualising antibodies by labelling them. Contemplating whether antibodies could be responsible for hypersensitivity reactions in rheumatic fever, Coons “considered that it might be easier to find the antigen than the antibody”, and that “what was required was a visible microprecipitate”. His idea received strong support from many researchers, including John Enders. But, rather than focusing solely on whether this would be beneficial to rheumatic fever research alone, Coons' supporters reasoned that labelled antibodies would also be exceptionally useful for pinpointing proteins in tissue samples—a function that had extraordinary potential in a wide range of applications. One of the researchers providing encouragement was Louis Fieser, a professor of organic chemistry at Harvard University. Initially, Coons replicated the work of John Marrack to couple antibodies to tetrazotised benzidine, a coloured dye. Although the antigen-binding properties of the antibodies remained intact, only a faint colour was visible when the antibodies precipitated in solution. To enhance antibody detection, Fieser prompted a collaboration between Coons and two other Harvard researchers, Hugh Creech and Norman Jones, who were already studying methods of protein conjugation. This research alliance proved to be especially rewarding: with Creech and Jones's expertise, Coons coupled anthracene isocyanate, a fluorescent dye, to antibodies within an antiserum specific for pneumococcal antigens. When incubated with the pneumococcal bacteria in solution and then excited by ultraviolet light, the antibodies agglutinated the bacteria and were visibly fluorescent. Coons had successfully labelled antibodies without disturbing their binding properties and antigen specificity. However, after testing the labelled antibodies in human and mouse tissue sections, Coons and colleagues discovered that the autofluorescence of the tissue was too similar to the fluorescence of anthracene to allow any distinction between tissue and antibody. Clearly, to develop a technique suitable for examining tissues, an alternative fluorescent dye was needed. Coons' next choice of label was fluorescein, a compound with a fluorescence discernible from tissue autofluorescence, but one that needed modification before it could be linked to an antibody. With more collaboration with researchers at Harvard University, Coons constructed a fluorescein–isocyanate compound and used this to label anti-pneumococcal antibodies. After confirming that the antibodies remained specific for their target bacterial strains and could be visualised clearly by their fluorescence, Coons and co-workers tested the antibodies on animal tissues. The results were a triumph. Unlike uninfected tissues, infected tissue specimens fluoresced brightly. Before long, the technique spread across research disciplines, and the specialties of immunology, infection, and cell biology were instantaneously enriched. During World War 2, Coons put his fellowship and research on hold to work as a pathologist in the US Army Medical Corps for 4 years. In 1946, he resumed his fellowship at Harvard, and eventually became an instructor in 1947 and a visiting professor in 1953. As visiting professor, Coons was elected as Career Investigator of the American Heart Association. His work remained focused on antigen localisation and improving methods of antigen detection, and also diffused into investigating the mechanisms of inhibiting antibody formation, the results of which were published in the journal Nature in 1959. Between 1960 and 1961, Coons became the 44th president of the American Association of Immunologists, and in 1961 he welcomed the new era of immunofluorescence in a review article published in the Journal of Immunology. Throughout the 1960s and 1970s, Coons' work in immunology formed a platform for the understanding of antibody formation and the development of immune responses in vivo. In 1970, Coons was appointed professor of bacteriology and immunology, and 1 year later in 1971 he was also appointed professor in the Department of Pathology. On Sept 30, 1978, he died of a heart attack aged 66 years. The techniques conceived and refined by Coons and colleagues have paved the way for immunofluorescence and immunohistochemistry, and adaptations in microscopes and cameras, and enzymatic and fluorophore labels have further enhanced staining resolution and our understanding of disease processes and structural biology. By harnessing the enigmatic proficiency of antibody specificity in the laboratory, Coons showed that almost any protein could be pinpointed within tissues and cells. His legacy continues today, and in an era of phenotyping, is becoming ever more consequential.