The Austrian-born American biologist Karl Landsteiner in 1901 was the first to classify human blood group system—ABO BLOOD GROUPS. The method of classifying the human blood on the basis of the inherited properties of red blood cells (Erythrocytes) as determined by their possession of or lack of the so-called antigens A (including AI and A,) and B. Persons may thus have type A, type B, type 0 or type AB blood. Antigens of other blood group systems may also be present.
