In 1984 Cesar Milstein and Georges Kohler were awarded the Nobel Prize for their discovery of hybridoma technology, a method leading to the production of unlimited quantities of biological reagents of "exquisite specificity" known as monoclonal antibodies. Focusing on this groundbreaking development in the recent history of the biomedical sciences, this volume offers a description of scientific activity that delineates both the local and general aspects of the development of scientific knowledge. Based on an extensive reading of the literature in the field, interviews with leading participants and on-site observation, the book follows events, materials and actors through a twenty-year period during which a laboratory technique was transformed into one of the most successful tools of modern biotechnology. Beginning with an analysis of the ambiguities surrounding the initial status of monoclonal antibodies, the book goes on to explore the various practices and forms of knowledge involved in the reproduction of hybridoma technology. The analysis of the worldwide diffusion of monoclonal antibodies and their consequent transformation by users is complemented by a close-up account of their adoption within two laboratories. The book ends with a detailed analysis of the patent disputes that have shaped the industrial destiny of monoclonal antibodies.