COMMENT OBITUARY (1918–2014) Immunologist and educator who discovered fundamentals of binding.

erman Eisen made fundamental an ultrasensitive method to measure the contributions to our understand- strength of binding — the binding con- ing of how the body’s immune stant, or affinity — of for Hsystem recognizes foreign structures. chemical entities such as dinitrophenol. In an almost 70-year career, he showed He showed that binding becomes stronger OF MIT COURTESY how antibodies bind to (surface the more time has elapsed since the first molecules on viruses and bacteria) and exposure to an , because cells pro- measured how and why such binding ducing more tightly binding antibodies are strengthens, a concept that now domi- preferentially stimulated as the amount of nates the field of vaccine design. antigen diminishes. After repeated expo- Eisen died in Cambridge, Massa- sure to the same antigen (‘booster’ immu- chusetts, on 2 November. He was born nization) the tightly binding antibodies are in 1918 into the Jewish community of synthesized without delay. Brooklyn, New York, one of four chil- In 1973, he was recruited as a founding dren, to parents who had emigrated from member to the newly established Center Eastern Europe. “I grew up with a sense for Cancer Research (now the Koch Insti- that anti-Semitism in the world around tute for Integrative Cancer Research) at us was pervasive, regarded as a fact of the Massachusetts Institute of Technol- life, like birth and death,” he later wrote. ogy in Cambridge. His research inter- At age 16, he was interested in chemistry ests broadened to include recognition but enrolled as a premedical student at by receptors for antigens on cells (NYU), persuaded known as T lymphocytes. He contributed by his father that “large companies in the to the discovery and characterization of chemicals industry did not hire . In the elusive T-cell receptor, and provided , however, a somewhat related field, US$3,600 per year, freeing him to do full- experimental and conceptual tools to show one’s destiny was in one’s own hands.” time research and to marry Natalie Aronson, the extraordinary sensitivity of ‘killer’ T lym- While recuperating from tuberculo- a paediatrician, and start what became a phocytes, capable of responding to the pres- sis during his university years, Eisen was family of five children. Working in the bio- ence of even a single antigen molecule as a deeply affected by two works: ’s chemistry department at NYU, Eisen, with means of eradicating a virus-infected cell. Arrowsmith (1925) and Charles Darwin’s On Fred Karush, showed that antibodies typi- At his house near Woods Hole, Massachu- the Origin of Species (1859). He was inspired cally possess two active sites that can bind setts, Eisen indulged his passion for garden- by a seminar in which he learnt that moving antigens. This permits the formation of ing, enjoying the biology and the aesthetics of a hydroxyl group on a benzene substituent aggregates that are eliminated from the body. what he nurtured. The author of an influential from one carbon atom to another dramati- However, if such complexes lodge in joints or textbook, General (1990), Eisen cally changed the compound’s effect on a cat’s in the kidney, they can cause disease. was a sought-after mentor for students, post- blood pressure. It revealed to him the connec- Next, Eisen moved to NYU’s department doctoral fellows and sabbatical visitors. tion between molecular s