MIT Nobel laureate Susumu Tonegawa, who deciphered antibody diversity, dies at 86

Susumu Tonegawa, the Picower Professor of Biology and Neuroscience at MIT and winner of the 1987 Nobel Prize in Physiology or Medicine, died July 11 at age 86. Tonegawa's Nobel-winning work in the 1970s solved a central mystery of immunology: how the immune system generates a vast repertoire of antibodies from a limited set of genes. He showed that antibody genes undergo somatic recombination, a process of cutting and rejoining DNA segments, during B-cell development, creating millions of distinct antibody variants from a finite genetic toolkit. The discovery transformed understanding of adaptive immunity and established the principle that genetic rearrangement drives immune diversity. Tonegawa later applied molecular and cellular approaches to neuroscience, pioneering work on memory formation and the role of the hippocampus. At MIT's Picower Institute for Learning and Memory, his lab identified neural circuits underlying memory engrams and demonstrated that artificial reactivation of specific neurons could recall a memory. Born in Nagoya, Japan, in 1939, Tonegawa earned his Ph.D. in molecular biology from the University of California, San Diego. He joined the Basel Institute for Immunology in Switzerland before moving to MIT in 1981. He received the Albert Lasker Basic Medical Research Award in 1985 and the Nobel Prize two years later. Colleagues described him as a rigorous experimentalist who bridged immunology and neuroscience with mechanistic precision.