ABO blood groups

What was discovered

By mixing sera and blood cells from colleagues he discovered that human blood agglutinates in fixed patterns, defining blood groups A, B and O (AB in 1902). It explained why transfusions used to be fatal.

Nobel Prize 1930.

What it led to

• safe transfusion and blood banks
• major surgery and war medicine
• human genetics (first Mendelian marker)
• forensic medicine and paternity testing

Built on

• Discovery of the red blood cell1658
• failed 19th-century transfusions
• Ehrlich's immunology

Made possible

• Blood bank1914–1937
• Rh factor1939-1940
• citrate transfusion

📄 Original publication

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