Thanks to him, we got to know blood groups: Who is Karl Landsteiner?

Karl Landsteiner (b. June 14, 1868, Vienna, Austro-Hungarian Empire - d. June 26, 1943, New York, USA) was an American immunologist and pathologist of Austrian origin. He received the 1930 Nobel Prize in Physiology or Medicine for his discovery of the major blood groups and his development of the ABO blood group system, which made blood transfusion a simple procedure in medicine.

While working as a researcher at the Vienna Institute of Pathology between 1898 and 1908, he discovered differences in the structure of blood in humans and revealed the dangers of inappropriate blood transfusions. In 1901, he showed that there are at least three blood groups in humans, based on the type of antigens that bind to the outer layer of the cell membrane in red blood cells; he named these groups A, B, and O. One year later, the AB group was found, carrying both A and B antigens and lacking AB antibodies. Landsteiner identified the M and N groups in 1927, and the Rhesus (Rh) factor, named after the monkey species in which it was first found, in 1940. The Rh factor was the basis for a series of reactions that could occur in the blood of the mother and the fetus, leading to miscarriage, stillbirth, or a fatal disease in the newborn.

Karl Landsteiner (14 June 1868 – 26 June 1943) was an Austrian-born American biologist, physician, and immunologist. He emigrated with his family to New York in 1923 for professional opportunities, working for the Rockefeller Institute.

Landsteiner's work made significant contributions to the development of forensic medicine; It enabled blood groups to be used as reliable evidence in paternity and murder cases. Proving that blood groups are transmitted from generation to generation through certain genes also provided an effective method for heredity and anthropology research.

Landsteiner taught pathology at the University of Vienna between 1909 and 1919, and at the Rockefeller Institute for Medical Research in New York between 1922 and 1943.

ABO system: According to this system, each person falls into one of four blood groups. The groups are A, B, AB, and 0. The separation is done by special proteins found in red blood cells and plasma. The proteins in the plasma are called "agglutinins" and those on the red blood cells are called "agglutinogen". There are two types of agglutinogens, called A and B, and two types of agglutinins, called α (alpha) and β (beta). A type A person carries A agglutinogen in his red blood cells and β agglutinin in his plasma. If this person's blood is given to a type B person carrying B agglutinogen and α agglutinin, the α agglutinins in the recipient's blood will combine with the donor's A agglutinogen and precipitate. This collapse occurs everywhere in the body and is incompatible with life. If the amount of blood given is very small, the resulting small amount of sediment blocks various vessels and causes damage to many organs.

Rh system: Rhesus protein, also known as Rh factor, is a special protein found in red blood cells. According to the Rh factor, two types of blood are distinguished, Rh (+) and Rh (-); that is, blood with or without Rh protein. Giving Rh (-) blood to an Rh (+) person does not cause any reaction. When Rh (+) blood is given to an Rh (-) person, no problems occur during the first transfusion. However, at this time, Anti-Rh antibodies against the Rh factor of the given blood are formed in the recipient's blood serum. The same situation applies to Rh (+) children born to Rh (+) father and Rh (-) mother.

The child's blood type may not be similar to its parents: The child's blood type is similar to that of its father or mother. Sometimes it is similar to both or dissimilar to both. If the child's blood type were not different from the blood type of its parents, there would be only two types of blood groups on earth. Because all humans are made up of a man and a woman.