The demonstration that density gradient-isolated large granular lymphocytes were responsible for human NK activity, made by Timonen and Saksela in 1980, was the first time that NK cells had been visualized microscopically, and was a major breakthrough in the field.
A demostración de que os linfocitos granulares grandes illados por gradiente de densidade eran os responsables da actividade de "asasinato natural" nos humanos fixérona Timonen e Saksela en 1980, e foi a primeira vez que as células NK foron visualizadas microscopicamente e foi un gran progreso nese campo.