1930 Nobel Prize in Physiology or Medicine — Karl Landsteiner

What You Will Learn in This Article

Even though it’s the same type of blood, you will understand why some combinations save lives while others cause death, and why the discovery of an Austrian pathologist who revealed this with a single test tube received the Nobel Prize 30 years later.

The Same Human Blood, Different Outcomes

In the late 19th century, blood transfusions were a gamble. While the idea of transfusing blood from one person to another to save a patient suffering from severe blood loss had been around for a while, the results were unpredictable.

Some patients survived. Others experienced chills during the transfusion, their urine turned dark, and they died within hours. The same procedure, the same type of blood, the same human. Yet, the results varied drastically.

At the time, doctors responded with statistical observations. They attributed the outcomes to “chance” or the “patient’s constitution.” Some even argued that transfusions should be banned altogether. The true cause of this dangerous procedure was revealed in a short paper in 1900, and its author received the Nobel Prize 30 years later.

The answer was surprisingly simple: human blood has different “types.” Mixing incompatible types causes agglutination.

The Landscape of the Time — Deepening the Great Depression

In 1930, the world was in the midst of the Great Depression. Just months after Black Thursday in the previous October, unemployment in the United States began to surge. In this year, unemployment in the United States was already approaching 9%, and it would soon rise to 25%. Banks were collapsing, savings were evaporating, and lines of unemployed people were growing in cities.

The situation in Europe was even more complicated. With unemployment in the Weimar Republic (Germany) soaring above 20%, extremist political forces were rapidly gaining ground. In the German elections of September of this year, the Nazi Party became the second-largest party. This was a critical turning point that would lead to Hitler's rise to power three years later.

Landsteiner’s homeland, Austria, was also in a state of severe political turmoil. He had already moved to the Rockefeller Institute in the United States in 1922, and he would receive this award in New York. It was a time when history was justifying his move. If he had remained in Vienna, he would have been in great danger due to his Jewish ancestry during the Anschluss, the annexation of Austria by Nazi Germany in 1938.

In the Soviet Union during this period, Stalin’s first five-year plan was being implemented, and forced collectivization and the Great Purge were beginning. The Holodomor, the Ukrainian famine, would occur in the following years.

If we look at the timeline in relation to Korean history, 1930 was the year after the Gwangju Student Uprising spread throughout the country. The Japanese colonial government expanded its crackdown to over 5,000 people, and intellectuals and students were widely affected. While the discovery that “human blood has different types” was being recognized with a Nobel Prize in Europe, in Korea, people with different ideologies were being imprisoned. The discovery that recognizes diversity and the politics that suppress diversity coexisted in the same era.

The Story of the Man — The Pathologist’s Method

Karl Landsteiner was born in Vienna, Austria, in 1868. He was born into a Jewish family but converted to Catholicism in his youth. This background would shape many critical moments in his life.

After graduating from the medical school at the University of Vienna, he chose pathology. Not a clinical doctor, but a pathologist. This choice was crucial. Clinical doctors see patients. Pathologists see tissues, cells, and blood. He was trained to approach the principles of disease through specimens and test tubes, rather than through living patients.

One of the routine tasks for pathologists at the time was investigating deaths after blood transfusions. When a patient died after a transfusion, the pathologist had to investigate the cause. Landsteiner saw these cases repeatedly. This repeated observation led him to ask a critical question.

“Why does this agglutination reaction occur only in certain combinations?”

At the time, he was also conducting research in bacteriology and immunology. It was a time when Paul Ehrlich’s antigen-antibody reaction theory was being established. The method he used to approach this question was remarkably practical: he mixed the blood of several of his colleagues.

The Blood of People Next Door

One day in 1900, he drew blood from several of his colleagues (including himself). He mixed each person’s serum with the red blood cells of the other people in test tubes. The results were surprising.

• In some combinations, nothing happened.
• In some combinations, visible agglutination occurred immediately — the red blood cells clumped together and settled.

When he organized this agglutination pattern, he found that it could be divided into four groups. He initially named these groups A, B, and C (later C was changed to O), and a fourth group, AB, was added later. Human blood has different types. This was the core of his 1900 paper.

He immediately summarized what this discovery meant if applied to safe transfusions today. Blood types must be matched before a transfusion. This would completely eliminate agglutination deaths. This principle was published in a 1901 paper and was recognized with the Nobel Prize 30 years later.

Key Achievements — Blood Viewed Through the Lens of Type Systems

Interface Mismatch

What Landsteiner discovered was remarkably similar to the type system in computer science.

When writing a program, suppose a function is defined to accept a specific type of input. For example, sqrt(x: float). What if you input the string "hello"? A type mismatch error will occur. The program will crash.

The human blood system also works on the same principle. Plasma antibodies are designed to accept only specific red blood cell surface antigens.

• Type A plasma causes agglutination (error) when it encounters red blood cells with the B antigen.
• Type B plasma agglutinates when it encounters red blood cells with the A antigen.
• Type O plasma agglutinates both A and B. (Rejects all types → opposite of a universal recipient, a universal donor)
• Type AB plasma accepts both A and B. (Accepts all types → a universal recipient)

The practical implication of this system is that type mismatch = immediate agglutination = death.

The CS analogy applies here in a straightforward way. Just as the compiler detects type mismatches at compile time, cross-matching tests before transfusions prevent the risk of agglutination in the human body. This is the test that is now performed as a standard before transfusions in hospitals. The patient’s serum and the donor’s red blood cells are mixed in a test tube in advance to confirm that there is no agglutination before the transfusion. It is the same principle as “passing QA before release.”

However, this analogy breaks down here. The type system in software is something we design explicitly. However, the blood type system is created by evolution, and why this system exists is not yet fully understood. The most plausible hypothesis is that it is related to resistance to different pathogens, but this has not been definitively proven. What we have discovered is the rules (agglutination pattern) of this system, but not the reasons why these rules were created.

The 30-Year Delay

Landsteiner’s discovery was in 1900, and the Nobel Prize was in 1930. This is a 30-year delay. Why was it so late?

First, the immediate impact of the discovery was not initially recognized. In the early 1900s, blood transfusions were still rare. The full impact of the discovery was not felt until the First World War, when blood transfusions became a common procedure. It was only after the 1914-1918 war made transfusions a common procedure that Landsteiner’s discovery began to save countless lives every day.

Second, it was due to the Nobel Committee’s cautious verification principle. The committee verified whether the discovery was truly valid and whether there were any alternative explanations before awarding the prize more than 25 years later. This is similar to the pattern in the previous year’s award to Eijkman and Hopkins (32 years/17 years delay). The long verification period created the credibility of the award.

The Rh Factor — A Second Discovery

Landsteiner’s story did not end with the Nobel Prize. Six years after the Nobel Prize, in the year he turned 68, he discovered the Rh factor (1937-1940). Rh is named after the Rhesus monkey. It was discovered that the Rh positive/negative factor was the cause of blood type incompatibility between pregnant women and fetuses.

He made a second discovery that had a greater clinical impact than his first discovery, after receiving the Nobel Prize. This is a rare case in Nobel history. It was the result of his long-held pathologist’s approach.

Why Is It Important?

Landsteiner’s Nobel Prize is still relevant today at three levels.

Clinical level: Today, blood types are matched before transfusions around the world. His 1900 paper is the reason why hundreds of millions of transfusions are performed each year, and agglutination incidents are rare. Emergency surgery, massive bleeding in mothers, chemotherapy for leukemia — none of these would be possible without safe transfusions.

Conceptual level: The concept of “different physiological types existing in the same species, humans.” This concept has since been extended to the basis of tissue compatibility antigens (HLA), genetic diversity, and personalized medicine.

Research method level: His approach was to “look at the test tube instead of the patient and find the principle.” It is a case where test tube experiments provide answers to problems that cannot be answered by clinical observation. Today, this approach is the basis of diagnostic medicine. Blood tests, genetic tests, PCR — finding answers in test tubes and applying them to clinical practice.

He left us with a lesson: “Don’t look for the reasons why something doesn’t work in the patient, but look for the principles.” In the past, if a transfusion failed, it was dismissed as “the patient’s constitution.” Landsteiner found the principle of the failure, and when that principle accurately explained the conditions of failure, the failure became preventable. In debugging software, instead of dismissing it as an “environmental issue,” finding the underlying principle creates a real solution.

Even as you read this sentence, blood transfusions are being performed in hospitals around the world. The reason why these transfusions are safe is rooted in the experiments in which colleagues mixed their blood in test tubes in a pathology laboratory in Vienna 100 years ago.

Summary of the Discovery of Blood Types: Landsteiner observed the agglutination pattern by mixing the serum of several people in test tubes and demonstrated that human blood is divided into four groups: A, B, O (later AB). This discovery changed blood transfusions from a gamble to a safe procedure.

→ Experience it with coding: DevBench — Type Mismatch and Interface Validation → Learn about CS concepts: DryBench — Type Systems and Compile-Time Verification