He also observed that sheep RBC were haemolysed when exposed to human serum.
In 1901 Karl Landsteiner discovered the blood group ABO system of human erythrocytes. He showed that people could be divided into three groups on the basis of whether their red cells clumped when mixed with separated sera from other people.
Landsteiner found that there are substances in the blood, antigens and antibodies that induce clumping of red cells when red cells of one type are added to those of a second type.
Since then, the realization that red cells posses proteins that can be used to classify them into various blood groups has revolutions medicine.
As a result of Karl Landsteiner discovery typing and cross matching became routine procedures for determining the suitability of a donor for a specific recipient. Steiner won a Nobel Prize in 1930 for his discovery.
Discovery of blood group
