Blood types were once thought to be with people for life. And, in almost every case, they're still thought to be with a person for life. But there is one patient whose blood type actually changed. A liver transplant, apparently, has a shot of changing a person's blood type.
There was once a simple time in human history when everyone had just one blood type, and that blood type was O negative. It wasn't called O at the time, of course, because even if anyone was looking at it, it would just have been blood to them. But life kept up its usual trick of evolving, and suddenly, on the surface of the lovely, smooth, red blood cells were little agglutinations of protein. There was what's now known as the Rh factor, the thing that turns O negative blood into O positive blood. Then there were other little clumps of protein, which separated Rh positive blood and Rh negative blood into A and B types. For the vast majority of history, only the Rh factor caused any bother. The system of an Rh negative woman who became pregnant with an Rh positive baby could see the infant's blood type as an outside body, and attack it. This was such a selector that today eighty-five percent of people are Rh positive.
Meanwhile, A and B types only began troubling humankind by the time blood transfusions and organ transplants were happening. (Before that, any human blood or organs entering the body generally came via the stomach, which isn't that fussy about blood types.) Again, the immune system would attack the strangely bedecked blood cells and cause medical problems. Type O patients, roughly forty-five percent of the population, could give out their blood and organs, but couldn't receive anyone else's. The Rh factor of the blood depended on what type of medical procedure was being done.
And so the world became concerned with these little blobs on blood, and with the genes that caused them. Since it was genetic, blood type was for life, and there was no way around the variations (Two more of which were found just recently. The Junior and Langereis, which affect about 50,000 people in Japan.) so there wasn't anything to be done except finding universal O negative donors and draining them like Capri Sun juice bags. So imagine people's surprise when they found out that blood type can change.
Technically, it depends on what people mean by blood type. The genes don't change. However, people noticed that after bone marrow transplants, recovered patients sometimes slowly developed their donor's blood types. The marrow was used making one kind of blood, and it would continue, slowly filling people with cells that didn't match their genotype. That made sense. Scientists had put a new manufacturing center in their patient. It would make what it had always made. It also made a certain, if surprising, sense that cancers that affected blood and bone marrow could change a person's expressed blood type as well.
Then an infant with rubella, who has been typed as A many times in the first eight weeks of her life, suddenly lost her A agglutinations. At four months old, her blood type had actually changed. This may sound eerie to us, but it was good news to those who wanted to turn blood into a fluid that can be donated from anyone to anyone, including to and from one of those 50,000 people in Japan. Anything that could shear off agglutinations could make every bag of blood into a universal donor bag. It just, preferably, shouldn't be rubella.
After years of searching, the best candidate for an agglutination-snipper came from a special mushroom. (No, not that one.) An enzyme isolated from fungi was found to turn any blood, any blood at all, to type O, and it did it while the blood was in the bag, not in the patient. This can change blood into a fluid that can be given to anyone, and given the shortages at blood banks, anything that made blood more available to all patients is a good thing. The method is still being tested, but hopefully blood will become a lot more common soon.
But there is still one extraordinary blood type change mystery still out there, in the form of what today is a nineteen-year-old girl. As a nine-year-old, the girl's liver failed. A transplant liver was found, and the surgery was successful. Unfortunately, the girl began to get sick on the drugs that she had to take to force her body not to reject the new liver. Rejection is a huge concern for all donors. People have to take anti-rejection drugs their whole lives. Sickening immediately when taking them was a very bad sign. And then scientists typed her blood. The girl had spontaneously changed her blood, or rather her liver had spontaneously changed her blood. Stem cells from the liver got to her bone marrow, and then to her entire immune system. Slowly her blood type change from O negative to O positive, and her body accepted the liver. She was taken off the drugs, since she didn't actually need them anymore. Doctors called it an one-in-six-billion event. It would be great, for many transplant patients, if someday we could make the odds a little better than that.
Top Image of Blood Cells: National Cancer Institute
Second Image of Red and White Blood Cell: National Cancer Institute