When you're in need of a blood transfusion, you'll be given blood that matches the blood your own body produces. But this wasn't always the case. The reason we know about it is because of an Austrian and American biologist by the name of Karl Landsteiner, who discovered the blood groups in 1901.
Landsteiner, who died in June 1943, would have been 148 years old on June 14.
Prior to Landsteiner's discovery, blood transfusions had been attempted as early as the 17th century. Successful transfusions were conducted between animals, but when attempts were made to transfuse animal blood into humans, the human immune system rejected the blood. This can get fatal. The host's antibodies can attack the new red blood cells, breaking them down and causing blood to clot in the veins.
This can occur when a transfusion recipient is given incompatible human blood, too. While some successful human transfusions had taken place in the 19th century, it was largely by luck that they did succeed, and many did not.
You might not know the name Karl Landsteiner, but his discoveries have saved the lives of so many millions of us.
In 1901, Landsteiner discovered the existence of blood types A, B, AB and O, and that people of the same or compatible types can receive transfusions from one another. The first successful blood transfusion occurred in 1907 as a direct result of his work, which led to advances in medicine, therapies, and surgery.
Landsteiner is also credited with laying the groundwork, together with fellow scientist Erwin Popper, that led to the discovery of the polio virus. This was the first step towards developing a treatment for the disease which affected millions of children worldwide.
On what would be his 148th birthday, we thank you, Karl Landsteiner, for helping us lead longer, healthier lives.