The history of blood
After you go for a blood donation, you get a little letter through the post, telling you, among other things, your blood groups. But what are those, and how did we find out about them? Chris Smith was joined in studio by Elise Burton, an historian with an interest in genetics, at Cambridge University...
Elise - Well, the first blood groups to be defined was the ABO blood group system, which is the most well-known. And it was discovered right around the turn of the century by a scientist working in Vienna named Karl Landsteiner. And what he found at that time was only three blood types, because he was working with only 22 people and his sample didn't include the AB blood type.
Chris - Oh. So how did he actually fathom that there might be differences in blood groups in the first place? Because it's not intuitive to think that, when you see this red stuff coming out of people, that there may be differences.
Elise - That's right. The science he was working with, the context he was working in, was when blood transfusion was not at all a common thing to do and it was not a very successful medical procedure. What he did was try to understand why sometimes, when blood transfusions were attempted, the blood would coagulate or clump together and cause really severe reactions that would make the transfusion fail. So what he did in his first experience was really just take samples from two different people at a time, and mix them together to see if he could find a pattern; you know, some sort of logic for when the blood would coagulate or not.
Chris Obviously this is a bit of a volte-face from earlier medical practices where people were really keen on getting blood out of the body. So when did that switch-around happen, and people realised it's pretty important to keep hold of your blood, and rather than blood-let and take it away, actually we wanna put some back? When did that happen?
Elise - That was really in the 19th century, especially later in the 19th century, when people started having a better idea of how blood pressure worked, and the importance actually of maintaining constant blood pressure; in the event that too much blood was let out, that was recognised as a serious problem. But at the time, in the 19th century, people didn't actually agree necessarily that you should be putting blood back into people. They would actually inject people with things like milk with saline solution, that was a popular one, and worked well for some reasons; and sometimes they would try to inject non-human blood as a replacement.
Chris - I was going to say, did they go down the animal route? Because they'd say, “well this looks the same,” and they had microscopes, they would have been able to see there are cells in there, and they would have looked grossly the same. So it was presumably something that people logically tried, “well let's put some pig blood or sheep blood into a person and see what happens”?
Elise - They did indeed try that out. And it really wasn't until World War One when blood transfusions using human blood became an increasingly routine procedure, and everyone came to an agreement that in fact human blood is the best thing to use in a transfusion.
Chris - And were they adopting those techniques of knowing which bloods were compatible or not at that time, or was it still very much a potluck thing? Where people would say, “this guy's bleeding to death, he needs blood, we’ll just give him some,” and take the first person they come to and just say, “hold your arm out”.
Elise - Well this is an interesting story. So in the lead up to World War One, between 1900 when they were first discovered and 1914, Landsteiner himself recognised that it was probably very important for a transfusion that you should test the donor and the patient and try to come up with compatible matches. But a lot of physicians didn't necessarily agree that that was important, because usually the rare conditions under which they would even consider a transfusion were so dire and so time sensitive that they didn't have time to check for compatible blood type. The test that Landsteiner developed would take an entire day to get results.
Chris - And so what would they do? Just literally couple one person up to another?
Elise - Yes. In fact some of the early techniques for direct blood transfusion, they would literally sew together the artery and the vein of a donor and a patient.
Chris - Goodness. How long did... how did that work out? I would have thought that the donor wouldn't last terribly long either, because you're going to hose out most of your circulating volume!
Elise - Well it was an extremely dangerous procedure, and delicate.
Chris - I bet it was!
Elise - And it required a very well-trained surgeon to even link up the blood vessels in the first place. And yes, it was found that this was not at all sufficient for an emergency medical situation.
Chris - So when did things become more standardised and organised, so that actually we had an idea as to what these blood groups were and what you could and couldn't do in terms of donors and recipients; and also having blood banks, so we store blood, along the lines of common practice today?
Elise - World War One was an incredibly important time for the development of all of these things. So it was in the context of war where you had a lot of guinea pigs, in the form of unfortunately maimed soldiers, where these physicians could do a lot of experimental work. For example, how to keep blood from coagulating through the addition of chemicals like sodium citrate, for example; much, much faster ways to test for blood types so that you could test it within a minute, for example. Those were all things that were developed during the war. And also indirect procedures, where you could withdraw blood using syringes and later have it available for other people to accept as a transfusion. That all happened in the later war period, 1916 to 1918.
Chris - And then what happened since then to bring us to the present era? Because obviously this field has exploded since then and we know the value of blood, but we've learned a lot more about it: we know a lot more about certain diseases that can be inherited that can affect the way the blood works; we know a lot more about certain things that you can be exposed to when you're pregnant, for example, which will affect your likelihood of having problems later.
Elise - Well it was actually in the 1930s and 1940s, with the addition of certain mundane technologies like refrigeration, that we were able to develop institutions like blood banks that would enable you to study blood for longer periods of time without constantly needing fresh infusions from a ready stream of donors. So it was technologies like that in the 30s that were really important. And also the development of an idea of medical genetics which really boomed in the 1940s and after. The blood groups are important to that story because in 1910, that was when it was first found that the ABO blood types are inherited according to a Mendelian pattern. Until then no-one had proved that Mendelian genetics actually apply to any human characteristic.