by Hp Newquist
Lambs’ blood was used in some of the first transfusions.
However, Denis’s fourth patient ultimately died—he had received several transfusions to try to cure his insanity—and the man’s wife accused Denis of killing him with the transfusion. She took Denis to court, and the case made headlines all over Europe. People got very nervous about whether transfusions were really a good idea (even though there were signs that the woman had poisoned her husband), and governments throughout Europe soon banned all transfusions.
Like so much that had occurred with blood research prior to the 1800s, Denis had been lucky. Animal blood is actually incompatible with human blood because it has completely different elements in it even though it looks the same. What had probably happened was that Denis’s patients’ own blood had responded to the invasion of foreign blood by quickly attacking it and trying to destroy it. That’s what blood does to keep the body healthy. By triggering this reaction during the transfusion, the patients’ bodies may have also overwhelmed the original maladies that the patients were suffering from. But some patients didn’t survive, showing that there was something inherently wrong with using animal blood.
After Denis’s trial, no one attempted to perform transfusions for nearly two centuries. In the meantime, science finally figured out what blood really was.
CHAPTER 4
Smaller Than Sand
Anton van Leeuwenhoek is one of the most important figures in the entire history of science. He was born in the Netherlands in 1632 and did not go to medical school or study to be a scientist. He made his living making and selling cloth.
One of the tools used in producing cloth during Van Leeuwenhoek’s time was a strong magnifying glass. It allowed makers to examine the fine threads and weaving in their cloth to determine how well made it was. Van Leeuwenhoek was so fascinated by these magnifying glasses that he learned how to make them himself. It was not easy; it required that he learn how to handle and shape glass. But Van Leeuwenhoek created a way to make his lenses stronger than those anyone else had ever made. In fact, they were so strong that he could see things that had never been seen before, such as cells and bacteria. What Van Leeuwenhoek had done was create the first working microscopes.
Anton van Leeuwenhoek was the inventor of the microscope.
Van Leeuwenhoek looked at everything he possibly could, from pieces of stone and coffee beans to saliva and blood. While examining blood, he saw red cells, very distinct objects in the blood that no one knew about. He described their shape and even calculated the size of the cells as “25,000 times smaller than a fine grain of sand.” He also was able to see and identify capillaries, the very tiny blood vessels that ran like threads through the human body.
Several doctors had seen glimpses of these tiny parts of the human body before Van Leeuwenhoek. They had used their own simply constructed microscopes, but no one had the same close-up view—or written up the precise descriptions—that Van Leeuwenhoek had. And he wasn’t even a scientist!
Van Leeuwenhoek began sending letters to medical and science groups around Europe. Many of them wouldn’t believe or even consider his findings because he was a cloth maker. However, with each discovery—and he made hundreds of them—it appeared that Van Leeuwenhoek had truly done something that scientists had never done before: he had viewed the microscopic world.
An example of an early microscope by Van Leeuwenhoek.
Eventually, his microscopes and his studies made Van Leeuwenhoek famous, and he was soon honored all over the globe. He never published books like other scientists—he always put his findings in letters—and remained a cloth maker until he died. He claimed to have pursued his study of the invisible world for the sheer love and wonder of it.
The invention of the microscope and the discovery that blood was made up of tiny cells was exceedingly important to scientists. They could now use microscopes to see what blood was made of, and, they hoped, how it behaved and what it did. But they had a long way to go, and doctors continued with many of the practices they had used for years, such as bloodletting.
Red blood cells under a microscope.
LETTING GO OF BLOODLETTING
Most of George Washington's blood was drained from him in the hours before he died.
One of the reasons bloodletting had remained popular was that doctors didn’t know what else to do—bloodletting had always worked, or so they thought. But doctors and hospitals didn’t keep detailed records about how successful bloodletting was. All they knew was that sometimes it worked and sometimes it didn’t. They didn’t have data on how often bloodletting saved a patient, or even which kinds of patients responded positively to the treatment.
With the discovery that blood was more than just a red liquid that sloshed around inside the body, doctors and patients started wondering if taking blood was always such a good idea. The question became even more urgent after George Washington was treated with bloodletting—and then died from it.
On December 12, 1799, a little over two years after he had finished serving as the first president of the United States, Washington was out riding his horse during a violent winter storm, and didn’t bother to take off his wet clothes or warm himself when he returned home. (While nasty weather and dampness do not cause colds, they do weaken the body’s immune system, making people vulnerable to attacks by viruses and bacteria.) During the night, he contracted a bad cold, and had a nasty sore throat and fever when he woke up on December 13. His doctors were called, four of them, and decided to start bloodletting, which Washington approved of. Over the course of the next two days, about five pints of Washington’s blood were drained from him. That was more than half of all the blood in his body. On the night of December 14, Washington died.
An illustration of a bloodletting procedure.
We know now that even a severe cold and sore throat can be treated simply; often bed rest is the best medicine. Bloodletting, though, seemed to be the preferred treatment at the time.
However, several of Washington’s doctors felt that maybe they had taken too much blood. Washington was sixty-seven years old when he died, and his doctors realized that the massive bloodletting, done over the course of two days, might have been a strain on his body. One of the doctors had actually stated that Washington was too weak to undergo bloodletting, but the other doctors outvoted him. In later years, the doctors privately admitted that bloodletting the former president was a mistake.
Washington’s death didn’t stop the practice of bloodletting, but it did give doctors a grim reason to start thinking about its supposed benefits more seriously. The procedure continued, perhaps not as frequently as before, but doctors still didn’t have anything they thought would work better.
During the mid-1800s, in the years after Washington’s bloodletting, scientists proved that the body wasn’t controlled by humors or the proper balance of fluids in the body. They discovered that the microorganisms that invaded the body, such as infectious bacteria and viruses, were the main cause of sickness. Microscopes that had improved on Van Leeuwenhoek’s design allowed researchers like Louis Pasteur to see how these organisms grew and how they invaded living beings and poisoned food. Pasteur and many others began developing medicines to combat these dangerous organisms.
The ability to fight diseases with specific medicinal drugs significantly changed the way doctors worked. In just a few decades, medicines developed in research labs replaced medical procedures that had been used for centuries. By the end of the 1800s, bloodletting had fallen out of favor with the medical profession, day in some underdeveloped parts of the world, but it works no better than it did thousands of years ago.
TRANSFUSION
During the 1800s, as the importance of healthy blood became more apparent, doctors realized that blood loss was a very bad thing for humans. Any amount of lost blood—whether by accident or by bloodletting—might be dangerous to a patient’s health. One doctor who believed this was a British physician named James Blundell. He had at
tended to many women who died during childbirth. He felt that in many cases, the amount of blood lost during childbirth might have been a factor in their deaths. There is always a certain amount of blood that a woman loses when giving birth, but Blundell found that the ones who died often had additional bleeding. He wondered if replacing that blood might have saved them.
A woodcut of a woman in childbirth. In the background, men are reading the stars to predict the baby’s future.
Despite the international ban on blood transfusions, Blundell began to experiment with ways to put healthy blood back into individuals who had lost a lot of their own blood. Like those before him, he first experimented with dogs, and his research showed some success. In 1818 a man was brought to him who was bleeding internally; the patient was surely going to die if something wasn’t done. Blundell took the opportunity to get blood from several people he worked with, and injected it into the man by using a syringe. The man died anyway.
Despite this failure, Blundell was convinced that blood loss could be corrected by injecting patients with fresh blood. He attempted the process several more times. In most cases, the patients died, but in other cases, the recovery was dramatic. He performed fewer than twelve transfusions altogether, and half the patients—who most certainly would have died otherwise—lived. This was a better percentage of recovery than had been seen during those years when transfusions had been done with animal blood. Plus, Blundell was methodical in his processes, determined to replace lost blood and transfusing not just for the purpose of balancing the humors.
His success rate gave other doctors the courage to start their own investigations into blood transfusion. Many of them used the instruments that Blundell had developed to help with the process, such as devices that safely removed blood from donors before injecting it into a patient.
By the end of the nineteenth century, bloodletting was all but finished and transfusions had become popular again. The success rate was still not as high as most doctors wanted, and they couldn’t figure out why. After all, wasn’t all human blood the same?
No, it wasn’t. It would take one more discovery for the mystery surrounding blood transfusions to be solved.
Karl Landsteiner discovered that there were several types of blood. His native Austria honored his work by placing his image on a stamp.
That discovery came from Karl Landsteiner, a scientist in Austria. Landsteiner knew a lot about blood. He had performed thousands of autopsies, the procedure that is sometimes used in unusual or mysterious deaths to determine how a person has died. In 1900 Landsteiner saw something strange in his lab, where he was storing blood samples in test tubes. These samples contained blood from different people, all of whom were healthy donors. But the blood in some of the tubes was clumping, forming Jell-O-like particles.
He and others had seen this before, but had figured the clumping occurred only in unhealthy blood. Yet none of these samples had come from sick people. Why was the blood clumping?
Landsteiner began doing experiments in his spare time where he mixed different people’s blood samples together. Some clumped up and became gluey, a process called agglutination, and others remained wet and liquid. He studied the blood with a microscope and took copious notes about the samples.
Blood is stored in test tubes so that it can be viewed and tested.
Landsteiner found that some mixed samples got along fine. In others, the red cells from one person exploded when they came into contact with another person’s blood. It was a strange reaction: this bursting of blood cells usually happened only when cells were infected or were trying to fight off disease. Landsteiner determined that in these samples, one blood sample must be fighting off another.
He realized that the blood samples were fighting because they were different. The difference was in a chemical that red blood cells had on their surface to protect them from infection; the presence or absence of this chemical
Four types of blood each divided into two groups.
* * *
BLOOD TYPES
The four blood types— A, B, AB, and O, known as the ABO blood group—are distinguished by a specific kind of protein found on the outer layer of an individual's red blood cells. It breaks down like this: People with type A blood have a coating of a protein known as an A oligosaccharide attached to their red blood cells. People with type B blood have a coating of B oligosaccharide attached to their red blood cells (RBCs). People who are type AB have both A and B oligosaccharides on their RBCs. People with type O have neither A nor B oligosaccharides in their blood. These types are determined by a person's genetic makeup and cannot be changed.
An interesting thing occurs within these groups, though. While it is best to match blood types—such as with type A getting a transfusion from someone with type A—some of these types are interchangeable. For example, people with type AB blood can use blood from every other group, but no one else can use type AB. People with O blood must get blood from another O person, but O blood can be used with all other types. For this reason, type AB is called universal recipient blood and type O is called universal donor blood.
Blood donors recipients
The blood of rhesus monkeys led to the discovery of “positive” and “negative” blood types in humans.
Below the ABO category is a subgroup based on what is called the Rh factor. Your Rh factor is determined by whether or not your blood has a particular molecule that fights off certain kinds of cells, such as those produced by bacteria. If you have this molecule, then your blood is called positive. If you don't have it, the blood is typed as negative. So a person who has type O blood without the Rh factor is type O negative. The term “Rh factor” comes from the initial discovery of this molecule in the blood of rhesus monkeys.
* * *
created four kinds of blood. Landsteiner and his assistants called these blood types A, B, AB, and O. It turned out that everyone in the world had blood that fell into one of these four primary groups.
With the knowledge that people had different types of blood, the approach to transfusions took a huge turn. Doctors now under- stood that they had to put the correct blood type into their patients. It wasn’t the method of transfusion that had been causing problems; it was the fact that different blood types attacked each other when they came into contact. When that happened, patients died.
A wounded U.S. soldier is given a blood transfusion during World War I.
Using a simple test that involved mixing the patient’s blood with known samples to see whether it clumped or not, doctors could quickly determine the correct blood type. Suddenly transfusions were saving many lives. This was especially true in the last few years of World War I, when blood was used throughout Europe to help injured soldiers who had lost a lot of it on the battlefield. By that time, people had started donating their own blood to help save the lives of the troops.
A Red Cross poster asking for blood donations to help soldiers in wartime.
It had been nearly three hundred years from the days of animal blood transfusions, which routinely killed patients, to a world in which the blood from one person could immediately save the life of another. Science and medicine had finally found out how essential blood was to keeping people healthy, and how to use it to help them recover from serious injuries and illnesses. Blood transfusions became one of the most important medical procedures ever invented.
There was no longer any doubt that blood was the most important part of the body. Technology had allowed scientists and doctors to uncover the mysteries hidden in blood. Now you’re going to discover exactly what your blood does as it makes its way through every part of you.
CHAPTER 5
MAKING BLOOD
The best way to describe what blood is and does is to follow it through the body. As you read the next few chapters, take a moment to stop every once in a while and think about the fact that everything we’ll be talking about is happening in your body right this instant. Stop to feel your heartbeat or to consi
der the blood flowing into your brain and through your liver. Look at the pulse of blood thumping through your wrist—and then touch it to feel the flow. Look at the bluish veins in your feet below your ankles and check out the red vessels inyour eyes.
It’s often difficult to think about the incredible things that blood does because you never see any of them, even though they are going on right under your skin. Blood touches everything in your body, from your eyes to your intestines. What is most significant about your blood is how it interacts with everything it comes into contact with. This includes the organs it passes through, the nutrients it carries, and even the diseases that it can sometimes spread. Everything begins, and ends, with blood.
