Alexandra RadulovichKarl Landsteiner (14 June 1868 – 26 June 1943) was an Austrian pathologist/immunologist responsible for the discovery of several blood groups in humans and the ABO system classification in 1901; a discovery that earned him the Nobel Prize in Physiology or Medicine 30 years later. At the age of seventeen Landsteiner was admitted to the medical faculty of the University of Vienna where his interest in chemistry grew and he adopted the method of approaching medical anonymity through the lens of a chemist. Always attracted by research, Landsteiner conducted studies on the influence of diet on blood composition, thus publishing one of his first articles while still a student. Having had an affinity with the nature of antibodies and the mechanisms associated with immunity, Landsteiner's experimental trials were conducted in an attempt to understand the reason behind the fatal outcome of blood transfusions in patients. He suggested that the cause of clotting could be attributed to the presence of agglutinogens (antigens) which he called A and B, which...