Do you know your blood type? Today, we take it for granted that people have different blood types. But not so long ago, most people believed all blood was the same – a fatal misunderstanding.
At a glance
- Karl Landsteiner’s research in the early 1900s led to the classification of blood into groups.
- The discovery transformed medical practices, enabling safer blood transfusions.
- Blood donations are vital for healthcare worldwide, but timely access to blood varies between countries.
In Bram Stoker’s novel Dracula, count Dracula attacks a young girl called Lucy at night. To save her life, Lucy receives blood from four donors and is given another chance to live.
Published in 1897, this is one of the earliest depictions of blood transfusion in literature. But what Stoker and his readers didn’t know was that people’s understanding of blood transfusions was about to change – completely.
Blood transfusions: a look back at history
The first known blood transfusions took place in Europe in the mid-1600s. Several attempts of blood transfusions from sheep and dogs to humans as well as between humans were carried out during this time. However, so many patients died from adverse reactions that blood transfusions were banned in France, England, and Italy.
In the early 1800s, a British doctor carried out the first successful human-to-human blood transfusion, when a woman suffering from post-partum haemorrhage received blood from her husband. Still, far from all blood transfusions went well, and during the remainder of the century they were only carried out as a last resort. Doctors were aware that blood donors needed to be healthy and fit, but they failed to understand why some transfusions worked and some didn’t. Even Alfred Nobel – the man behind the Nobel Prize – tried to solve the mystery in the 1890s, without success.
Then, in the first years of the 1900s, a young Austrian professor made a discovery that would change everything.
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1 (of 2) Karl Landsteiner.
Photo: Bachrach Studios. Nobel Foundation archive
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2 (of 2) Table of blood groups.
From Karl Landsteiner's Nobel Prize lecture.
Clumping of blood cells and the blood groups
Karl Landsteiner, at the time in his early 30s, was working with pathological anatomy and immunology at the University of Vienna when he made his first observations about clumping of blood cells, so called agglutination.
Landsteiner’s research involved extracting blood samples from his research staff. He wanted to see whether one person’s red blood cells clumped together when mixed with blood serum from another’s. His experiments showed that adverse reactions occurred when a recipient possessed natural antibodies to a donor’s blood cells. In these cases, he found that the red blood cells from the donated blood began to clump, or agglutinate.
In the recipient these agglutinated red cells could clog blood vessels and stop the circulation of the blood to various parts of the body, or crack open, leaking toxic contents out in the body, which could eventually be fatal.
From his research, Landsteiner classified people and their blood into three groups, now known as A, B and O, with a fourth group AB discovered soon after. He showed that to successfully transfuse blood, matching blood types was crucial: transfusions between compatible groups were safe, but mixing different types could be deadly.
Why blood groups matter
The discovery of blood groups completely changed the view on blood transfusions, and it didn’t take long before the first successful attempts were carried out. During WWI, blood transfusions were first performed on a large scale. Countless lives were also saved through surgeries, which previously had been unfeasible due to the blood loss involved.
Crime scene investigations were handed a helpful new tool, as dried blood samples could now be typed. Once researchers realised that blood groups are inherited across generations, Landsteiner’s discoveries also helped scientists to study human population variation, as well as rule out potential fathers via paternity tests. Blood groups also play an important role in organ transplantation. If the recipient has antibodies against the donor’s blood type the organ might be rejected, making blood typing crucial.
Karl Landsteiner was awarded the Nobel Prize in Physiology or Medicine 1930. During the rest of his career, Landsteiner continued investigating blood groups. In the 1940s, decades after his first discovery, he and collaborators discovered another blood group: Rh. Today, we know of over 200 minor blood groups, but the ABO and Rh systems are most important for determining blood compatibility.
Blood donations across the world
Blood donations are critical for medical treatments and for saving lives. But globally, many patients who need blood transfusions do not have timely access to safe blood. In 2023, the WHO reported that of the around 118 million blood donations collected yearly worldwide, 40% were collected in high-income countries – home to just 16% of the world’s population.
There is also a large difference in terms of transfused patients. In high-income countries the most frequently transfused patient group is 60+ years, while in low-income countries most transfusions are given to children under five.
Every year, World Blood Donor Day is celebrated on 14 June – Karl Landsteiner’s birthday – to encourage people to become blood donors and to honour the individual who made it possible.
Play the game
What happens if you get a blood transfusion with the wrong blood type? Play a game where you save patients’ lives and learn about human blood types and blood typing.