eli5: What happens when you get a blood transfusion with the wrong/incompatible blood type?
In: Biology
Your body begins to attack the foreign blood. Odds are if you had a blood transfusion, you needed the extra blood and your body destroying is both your body putting in extra effort and losing all that blood that just got added to you.
If you have type A blood, your blood has type A protiens on the blood cells. If you donate your blood to someone else, their body needs to already have those type A protiens, or else it sees a new protien is hasn’t seen before and attacks it.
It’s the same deal for type B, just replace protien A with protien B
Type AB blood has both A and B protiens on the blood cells. This is why an AB blood type can receive blood from anyone because their bodies are already familiar with both the A and B protiens, and knows not to attack it.
Type O blood has neither the A or B protiens, which is why type O blood can go to anyone, there’s no foreign protiens to detect. Type O people also can only receive other type O blood.
The Rh factor (positive or negative) is a different protien independent from the A, B, O blood type. There’s another protien, and if it’s positive, you have this Rh protien, and if it’s negative, you don’t.
An Rh negative person can donate the Rh positive person because there’s no new foreign protein for the immune system to attack. And Rh positive person can’t donate to an Rh negative person because the Rh positive blood will introduce a new protien that the recipient’s body will attack.
Putting all this together, O- can donate to everyone (universal donor). O+ can donate to anyone with an Rh positive blood type.
AB+ can receive blood from anyone (universal recipient) and AB- can receive blood from anyone with an Rh negative blood type.
A- can go to anyone with A or AB. A+ can only go to people with A+ and AB+
B- can go to anyone with B or AB, B+ can only go to people with B+ and AB+
AB- can only go to people with AB, and AB+ can only go to other AB+
There is one additional very rare blood type called Hh, or the Bombay blood type. These people can only donate blood to each other. There’s a missing antigen that the ABO system is built on.
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