Being type A or B essentially means you have either the A substance or the B substance on your red blood cells. Type AB has a bit of both, and Type O has neither. Now, our bodies like to defend against foreigners, and so they make antibodies against things that aren’t recognized as self. Usually you need to be exposed to something first, like when you get a virus, but in the case of the blood substances, you’ve already got antibodies in your blood against the substances that aren’t on your cells.
When you get transfused with cells that have a different substance on them (you’re Type A, and you get Type B cells, for example), your antibodies will bind onto them and destroy the cells pretty quickly. This process of cells being destroyed is called hemolysis, and it’s a very bad thing. That’s why Type AB can get any type of blood, and why Type O can only get Type O.
A transfusion reaction from mismatched blood will cause fever and chills, a drop in blood pressure, and renal damage from all the hemoglobin that’s floating around in the plasma when it should be inside red cells. It can also cause bleeding and micro-clotting in the blood vessels, which can kill the patient.
Which is why a lab will never take your word about your blood type. Even if you were in the hospital last week for blood transfusions. Even if you come in every week and they know you well and ask how your kids are doing when they see you. Before giving you anything, they will re-check your blood type and they will do a cross-match with the donor blood to make sure nothing bad will happen.
No one in the world knows my blood type. I wasn’t born in a hospital, so it wasn’t tested right away. I’ve never had a horrible accident or something that I needed a transfusion for. And I can’t give blood yet.
I don’t know if I’m CMV-. I do know that I’m AB+, which makes it seem rather pointless for me to give blood. I do, of course, but I still don’t feel I’m doing much good considering that anyone who can use my blood can use anyone else’s, too.
Apparently it also means I’m “both outgoing and shy, confident and timid. While responsible, too much responsibility will cause a problem. They are trustworthy and like to help others.”
Another O neg here. I give as often as I can, universal doner and all. Though us O negs really get the shaft. Universal doner, but can only take our own blood.
Well, if we’re talking whole blood, you’re right - anyone who can use your red cells could use any others too. But your plasma (the liquid part left over when we spin the blood to separate it) is valuable. Anyone of any blood type can use your plasma, because you don’t have any antibodies in it against the A and the B substances.
Blood donations produce more than just bags of whole blood. The blood gets spun down to get red cells to treat anemias, platelets to help clotting, and plasma, which contains clotting factors too.
Not only that, but if your AB blood is available for a transfusion to an AB person, it means that the A or B or O unit that would have been used instead goes to someone else.
