Jürg Tschopp 1951–2011

Jürg Tschopp Photo courtesy of Université de Lausanne. On March 22, the field of Immunology lost one of the great Biochemists of his generation a few months from his 60th birthday. Dr. Jürg Tschopp grew up in Basel in his beloved Switzerland. As a youth, he proved to be a gifted athlete. He was nationally recognized in the decathlon and, naturally, growing up a mere stones-throw from the Alps was a formidable skier. I discovered this—largely to my peril. Several times at many a meeting over the years, I unwisely attempted to follow his lead down one too many ‘‘challenging’’ slopes with sobering effect. Of the many memories of my interactions with Jürg, I recall with genuine affection our jousting in Swiss German with my limited, although colorful, vocabulary of around 20 words, acquired when I was a postdoc in Zurich years earlier. Those discussions were brief but nevertheless memorable. It was always clear to me that Jürg possessed a powerful combination of fearlessness, rigor, and excellence, three characteristics that are central to being a great scientist. Thus, his many contributions throughout a brilliant career came, in a way, as no surprise. Jürg received rigorous training as an undergraduate in chemistry and as a graduate student in biophysics at the renowned Biocentrum of the University of Basel, obtaining his PhD in Biophysics in 1979. Immunology caught his attention, and he decided to perform postdoctoral studies under the mentorship of Dr. H.J. Müller-Eberhard at the Scripps Clinic in La Jolla, CA. There, he did important work, showing that the lytic pore of complement was formed by C9 multimers. He continued in the complement field and in 1982 returned to his position as Assistant Professor at the Institute of Biochemistry at the Institute of Lausanne. During the early period of his work in Switzerland he published extensively and in part shifted his research direction to the nature of the lytic components of cytotoxic T lymphocytes (CTLs). His interests in these involved the study of the so-called granzymes, serine proteases that play a role in the CTL process. He cloned the genes of several granzymes and characterized their encoded proteins isolated from granules from cloned CTLs. This work on granzymes complemented his earlier work, in which he characterized a lytic pore-forming component, perforin, which mediates killing by CTL. Jürg’s work was influential in establishing the function of these molecules and in describing the acquisition of these cytolytic granules upon the induction of cytolytic activity in CTL. His work on these cytotoxic molecules was recognized not only in a substantial number of primary research publications in prominent immunologic journals but also in an influential review published in 1990 in the Annual Reviews of Immunology. His interest in this area led naturally to Jürg posing the question of whether perforin was the only pathway toward lysis, or whether other pathways played a role. Addressing this issue, in 1994 he published an important paper in which he showed that cytolytic T cell cytotoxicity is mediated through two lytic pathways, perforin and fas. This paper, published in Nature, established