Karl Landsteiner and the Discovery of the Major Blood Types

Karl Landsteiner
11/1/30-New York: Dr. Karl Landsteiner, at his desk.

 Bettmann/Getty Images

Austrian physician and immunologist Karl Landsteiner (June 14, 1868 — June 26, 1943) is most noted for his discovery of the major blood types and developing a system for blood typing. This discovery made it possible to determine blood compatibility for safe blood transfusions.

Fast Facts: Karl Landsteiner

  • Born: June 14, 1868, in Vienna, Austria
  • Died: June 26, 1943, in New York, New York
  • Parent's Names: Leopold and Fanny Hess Landsteiner
  • Spouse: Helen Wlasto (m. 1916)
  • Child: Ernst Karl Landsteiner
  • Education: University of Vienna (M.D.)
  • Key Accomplishments: Nobel Prize for Physiology or Medicine (1930)

Early Years

Karl Landsteiner was born in Vienna, Austria in 1868, to Fanny and Leopold Landsteiner. His father was a popular journalist and Viennese newspaper publisher and editor. The death of Karl's father, when he was only six years of age, resulted in the development of an even closer relationship between Karl and his mother.

Young Karl was always interested in science and mathematics and was an honor student during his primary and secondary school years. In 1885, he began studying medicine at the University of Vienna and earned an M.D. in 1891. While at the University of Vienna, Landsteiner became very interested in blood chemistry. Upon earning his M.D., he spent the next five years doing biochemical research in laboratories of well known European scientists, one of whom was Emil Fischer, an organic chemist who won a Nobel Prize in Chemistry (1902) for his research on carbohydrates, specifically sugars.

Career and Research

Dr. Landsteiner returned to Vienna in 1896 to continue to study medicine at Vienna General Hospital. He became an assistant to Max von Gruber at the Hygiene Institute, where he studied antibodies and immunity. Von Gruber had developed a blood test to identify the bacteria responsible for typhoid and contended that chemical signals on the bacteria were being recognized by antibodies in the blood. Landsteiner's interest in antibody studies and immunology continued to develop as a result of working with Von Gruber.

In 1898, Landsteiner became assistant to Anton Weichselbaum at the Institute of Pathological Anatomy. For the next ten years, he conducted research in the areas of serology, microbiology, and anatomy. During this time, Landsteiner made his famous discovery of blood groups and developed a system for classifying human blood.

Discovery of the Blood Groups

Dr. Landsteiner's investigations of interactions between red blood cells (RBCs) and serum of different people were initially noted in 1900. He observed the agglutination, or clumping together, of red blood cells when mixed with animal blood or other human blood. While Landsteiner was not the first to make these observations, he is credited with being the first to explain the biological processes behind the reaction.

Landsteiner performed experiments testing red blood cells against serum from the same patient as well as serum from different patients. He noted that a patient's RBCs did not agglutinate in the presence of their own serum. He also identified different patterns of reactivity and categorized them into three groups: A, B, and C. Landsteiner observed that when the RBCs from group A were mixed with serum from group B, the cells in group A clumped together. The same was true when RBCs from group B were mixed with serum from group A. The blood cells of group C did not react to serum from either groups A or B. However, the serum from group C caused agglutination in RBCs from both groups A and B.

Agglutination Type A Blood
This image shows agglutination (clumping) of type A red blood cells when mixed with ANTI-A serum. No clumping occurs when mixed with ANTI-B serum.  Ed Reschke/Photolibrary/Getty Images

Landsteiner determined that blood groups A and B have different types of agglutinogens, or antigens, on the surface of their red blood cells. They also have different antibodies (anti-A, anti-B) present in their blood serum. A student of Landsteiner's later identified an AB blood group that reacted with both A and B antibodies. Landsteiner's discovery became the basis for the ABO blood grouping system (as the name of group C was later changed to type O).

Landsteiner's work laid the foundation for our understanding of blood groupings. Cells from blood type A have A antigens on the cell surfaces and B antibodies in the serum, while cells from type B have B antigens on the cell surfaces and A antibodies in the serum. When type A RBCs contact serum from type B, A antibodies present in B serum bind to A antigens on the blood cell surfaces. This binding causes the cells to clump together. Antibodies in the serum identify the blood cells as foreign and initiate an immune response to neutralize the threat.

A similar reaction occurs when type B RBCs contact serum from type A containing B antibodies. Blood type O has no antigens on the blood cell surfaces and do not react with serum from either types A or B. Blood type O does have both A and B antibodies in the serum and thus reacts with RBCs from both A and B groups.

Landsteiner's work made blood typing possible for safe blood transfusions. His findings were published in the Central European Journal of Medicine, Wiener klinische Wochenschrift, in 1901. He received the Nobel Prize for Physiology or Medicine (1930) for this life saving accomplishment.

In 1923, Landsteiner made additional blood grouping discoveries while working in New York at the Rockefeller Institute for Medical Research. He helped to identify blood groups M, N, and P, which were initially used in paternity testing. In 1940, Landsteiner and Alexander Wiener discovered the Rh factor blood group, named for research conducted with rhesus monkeys. The presence of the Rh factor on blood cells indicates an Rh positive (Rh+) type. The absence of the Rh factor indicates an Rh negative (Rh-) type. This discovery provided a means for Rh blood type matching to prevent incompatibility reactions during transfusions. 

Death and Legacy 

Karl Landsteiner's contribution to medicine extended beyond blood groupings. In 1906, he developed a technique for the identification of the bacterium (T. pallidum) that causes syphilis using dark-field microscopy. His work with poliomyelitis (polio virus) lead to the discovery of its mechanism of action and development of a diagnostic blood test for the virus. In addition, Landsteiner's research on small molecules called haptens helped to elucidate their involvement in the immune response and the production of antibodies. These molecules ramp up immune responses to antigens and induce hypersensitivity reactions.

Landsteiner continued researching blood groups after retiring from the Rockefeller Institute in 1939. He would later change his focus to the study of malignant tumors in an attempt to find a cure for his wife, Helen Wlasto (m. 1916), who was diagnosed with thyroid cancer. Karl Landsteiner suffered a heart attack while in his laboratory and died a couple of days later on June 26, 1943.


  • Durand, Joel K., and Monte S. Willis. "Karl Landsteiner, MD: Transfusion Medicine." Laboratory Medicine, vol. 41, no. 1, 2010, pp. 53–55., doi:10.1309/lm0miclh4gg3qndc. 
  • Erkes, Dan A., and Senthamil R. Selvan. "Hapten-Induced Contact Hypersensitivity, Autoimmune Reactions, and Tumor Regression: Plausibility of Mediating Antitumor Immunity." Journal of Immunology Research, vol. 2014, 2014, pp. 1–28., doi:10.1155/2014/175265. 
  • "Karl Landsteiner – Biographical." Nobelprize.org, Nobel Media AB, www.nobelprize.org/prizes/medicine/1930/landsteiner/biographical/. 
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Bailey, Regina. "Karl Landsteiner and the Discovery of the Major Blood Types." ThoughtCo, Aug. 1, 2021, thoughtco.com/karl-landsteiner-4584823. Bailey, Regina. (2021, August 1). Karl Landsteiner and the Discovery of the Major Blood Types. Retrieved from https://www.thoughtco.com/karl-landsteiner-4584823 Bailey, Regina. "Karl Landsteiner and the Discovery of the Major Blood Types." ThoughtCo. https://www.thoughtco.com/karl-landsteiner-4584823 (accessed March 31, 2023).