antibodies and inspired the development of the field of antibody engineering, which was to lead to safer and more powerful monoclonal antibodies for use as therapeutics. Milstein's early work on antibodies focused on their diversity at the amino acid level, as well as on the disulfide bonds by which they were held together. Part of this work was done in collaboration with his wife, Celia. The emphasis of his research then shifted towards the mRNA encoding antibodies, where he was able to provide the first evidence for the existence of a precursor for these secreted polypeptides that contained a signal sequence. The development of the hybridoma technology coupled to advances in nucleic acid sequencing allowed Milstein to chart the changes that occurred in antibodies following antigen encounter. He demonstrated the importance of somatic hypermutation of immunoglobulin V genes in antibody affinity maturation. In this process, localized mutation of the immunoglobulin genes allows the production of improved antibodies, which make a major contribution to protective immunity and immunological memory. Much of his work in recent years was devoted to characterizing this mutational process with a view to understanding its mechanism. He contributed a manuscript for publication on this topic less than a week before he died. Quite apart from his own achievements, Milstein acted as a guide and inspiration to many in the antibody field, as well as devoting himself to assisting science and scientists in less developed countries. It is also worth mentioning that even though the Nobel Prize would have made him a wealthy man, Milstein did not patent his enormous discovery since he believed that it was mankind's intellectual property. According to his beliefs, his work did not have any economic interest, only scientific. Awards and honours In addition to the Nobel Prize in 1984, Milstein was elected a Fellow of the Royal Society (FRS) in 1975, was a fellow of Darwin College, Cambridge, from 1980 to 2002, awarded the Louisa Gross Horwitz Prize from Columbia University in 1980, won the Copley Medal in 1989, and became a Companion of Honour in 1995. In 1993, the Argentinian Konex Foundation granted him the Diamond Konex Award, one of the most prestigious cultural awards of Argentina, as the most important scientist in the last decade of his country. Personal life Milstein married Celia Prilleltensky in 1953. Milstein died early on 24 March 2002, in Cambridge, England, at age 74, as