Karl Landsteiner applied the sciences of biochemistry, pathology, microbiology, and immunology in medical research to great success during the first half of the 20th century. Although he is principally known for elucidating the major blood group antigens A and B and their isoantibodies for which he was awarded the Nobel Prize in Physiology or Medicine, Landsteiner made many other important medical discoveries. In that respect, he ascertained that paralytic poliomyelitis was due to a virus, the pancreas was damaged in cystic fibrosis, simple chemicals called haptens were able to combine with antibodies, and the Rh antigen that was later found to be the principal cause of hemolytic anemia of the newborn was found in most humans. Moreover, Landsteiner's book "The Specificity of Serological Reactions" was a precursor to the molecular revolution in immunology that occurred after Second World War. Finally, he was one of the leaders of the American Association of Immunology and of the Journal of Immunology.
Keywords: Karl Landsteiner; Rh factor; blood group antigens; genetics; haptens; hematology.