Jürg Tschopp stood apart from most of his colleagues in immunology in that his discoveries in fundamental research brought striking and almost immediate benefits to patients suffering from painful, debilitating diseases. Of his numerous findings, one led to a treatment for the autoimmune disorder systemic lupus erythematosus, and another brought dramatic relief to patients with gout.
An early milestone in his career was the characterization of the final step in a signalling pathway called the complement cascade. This is a crucial component of the innate immune response, which protects animals from an infection through a generic mechanism, rather than on the basis of previous 'remembered' encounters with an infectious agent.
In the early 1980s, immunologists knew that one protein involved in the complement cascade, C9, could kill bacteria, but how it worked was a mystery. Tschopp showed that C9 essentially drills holes in the cell wall of a bacterium by assembling into a pore within its cell membrane. Vital macromolecules leak out through the pore, and the bacterium quickly dies.
Subsequently, Tschopp found that a class of white blood cells called T cells destroy tumour cells or those harbouring viruses using a similar mechanism. In this case, these T cells release perforin, a channel-forming protein that inserts itself into the membrane of the target cell, allowing an enzyme called granzyme to enter the cell and destroy it.