Nils Jerne Nobel Prize in Physiology or Medicine, 1984 jointly with Georg Köhler and Cesar Milstein Date of Birth: 23.12.1911 Country: Great Britain

Biography of Niels Kaj Jerne

Niels Kaj Jerne, a Danish immunologist and recipient of the 1984 Nobel Prize in Physiology or Medicine, was born in London, United Kingdom. He was born into a family of Elsie Marie Jerne (née Lindberg) and Hans Jessen Jerne, making him both a British subject and a citizen of Denmark. During the early years of World War I, the Jerne family moved to the Netherlands. It was in Rotterdam, in 1928 at the age of 17, that Jerne obtained his Bachelor's degree.

In 1943, Jerne worked as a research fellow at the Danish State Serum Institute. He then spent two years studying physics at Leiden University, followed by a move to the University of Copenhagen. It was here that he wrote his thesis on the activity and affinity of antibodies, ultimately earning his medical degree in 1951. Jerne continued his work as a research fellow at the Danish State Serum Institute, where the primary focus of the institute was the study of antibodies and other mechanisms of the immune system.

In the late 19th century, Emil von Behring discovered that blood serum contains antibodies – protein substances that interact with foreign bodies, or antigens. Antibodies generally only interact with specific antigens, meaning the antigen-antibody reaction is specific. When an organism encounters a "foreign" antigen for the first time, a large number of antibodies are produced. Jerne discovered that if the organism continues to be exposed to the antigen, new antibodies are produced that form a stronger bond with the antigen. In his early work, he established that antibodies are not just proteins that interact with antigens, but components of an active immune system. He emphasized that the essence of immune reactions lies not in the production of specific antibodies against previously unknown antigens, but in the body's regulation of the production of a series of specific antibodies.

The question of antibody specificity arose after the research conducted by Karl Landsteiner in the 1930s. Landsteiner discovered that it was possible to induce the production of antibodies in mice that were specific to dozens or even hundreds of different chemical substances. Most scientists could not accept the idea that animals possessed millions of preformed antibodies, from which one specific antibody is selected upon contact with an antigen. It seemed more logical that antigens served as a kind of matrix for the formation of the corresponding antibody within the immune system. However, Jerne did not accept such "instructive" theories. He believed that antibodies are either selected from existing ones or gradually modified. As he later wrote, these ideas had a "Darwinian hue." Antibodies, in a way, undergo evolution through natural selection.

Until 1954, Jerne continued his work on antibody affinity and antigens at the Danish State Serum Institute. He then spent a year as a research fellow at the California Institute of Technology in Pasadena, collaborating with Max Delbrück. During his time in the United States, Jerne formulated the theory of selection for antibody formation. He proposed that there is always a large number of different antibodies present in the blood, and when a specific antibody encounters its corresponding antigen, a connection is formed that is recognized by lymphoid cells. As a result, these cells synthesize copies of the bound antibody. In 1957, Macfarlane Burnet developed Jerne's theory, suggesting that each antibody-producing cell can produce only one type of antibody specific to one antigen. When clones of such cells encounter their corresponding antigen, they are activated and begin to produce antibodies in large quantities. Burnet's clonal selection theory (which was also developed by researchers from the University of California, Joshua Lederberg and David Talmadge) became a leading concept in immunology in the 1950s. Jerne played a major role as a theorist in the development of this concept, identifying the potential consequences of different assumptions and creating a clear, unified terminology that allowed immunologists to communicate effectively.

From 1956 to 1962, Jerne was less involved in research. During this period, he held positions as the head of Biological Standards and Immunology Departments at the World Health Organization in Geneva. Additionally, from 1960 to 1962, he worked at the Department of Biophysics at the University of Geneva before moving to the University of Pittsburgh as the head of the Microbiology Department. In 1966, Jerne joined the Goethe University in Frankfurt, where he became the director of the Paul Ehrlich Institute. In Frankfurt, the pharmaceutical company "Hoffmann-La Roche" offered Jerne the opportunity to establish a new center for immunological research in Basel, Switzerland. Jerne served as the director of the Basel Institute for Immunology from its founding in 1969 until his retirement in 1980.

Despite his administrative responsibilities, Jerne continued to conduct productive immunological research. In the early 1960s, Jean Dausset, Baruj Benacerraf, and their colleagues discovered that the same cellular proteins that triggered the activation of the immune system, leading to organ transplant rejection, also determined the intensity of the immune response to other antigens. In 1971, Jerne proposed that antibodies are produced to recognize altered tissue compatibility antigens that are neither antagonistic nor toxic, and that the selection of corresponding antibodies occurs in the thymus – a non-flowing gland located in the upper part of the anterior mediastinum. While his hypothesis was proven incorrect for antibody-producing cells, it accurately reflected the function of T cells – components of the immune system that destroy infected and cancerous cells. Jerne's most significant contribution to immunology was his network theory, presented in 1974. To this day, it remains the most extensively developed and logical concept explaining the processes by which the body mobilizes to fight disease and returns to an inactive state once the disease is overcome. Jerne emphasized that there are far more varieties of antibodies than proteins and that the "dynamic state of our immune system is primarily self-referential, producing anti-idiotypic antibodies against our own antibodies (i.e., antibodies that correspond to the antigenic profile of our own antibodies)." Therefore, the reaction to a foreign body is not simply an increased production of a specific antibody, but rather a "disturbance of order" in an extremely complex self-regulating system.

In 1984, in recognition of the influence his innovative theories had on immunological research, Jerne, along with Georges Köhler and César Milstein, was awarded the Nobel Prize in Physiology or Medicine. Although Jerne's network theory did not lead to any sensational discoveries, it, along with his other concepts, formed the theoretical framework into which Köhler and Milstein's discoveries fit.

Colleagues admired Jerne for his love of the "philosophical problems of immunology," his ability to select the most relevant data from all available information, his talent for proposing bold yet clear hypotheses, and his "desire to insist on his correctness."

In 1980, Jerne retired, leaving his position at the Basel Institute for Immunology. He currently resides in southern France with his wife, Ursula Alexandra Jerne (née Koll), whom he married in 1964. They have two sons.

Jerne has received numerous awards and honors, including the International Gardner Foundation Award (1970) and the Paul Ehrlich Gold Medal from the University of Frankfurt (1982). He was a member of the Advisory Committee on Medical Research of the World Health Organization (1949-1968) and the Advisory Committee on Medical Research of the Pan American Health Organization (1963-1966). Since 1962, he has been a member of the Advisory Expert Committee on Immunology of the World Health Organization. Additionally, he is an honorary member of the Berlin Robert Koch Institute, a foreign honorary member of the American Academy of Arts and Sciences, and a member of the Royal Danish Academy of Sciences. He holds honorary degrees from the University of Chicago, Columbia University, the University of Copenhagen, the University of Basel, and Erasmus University Rotterdam.