O- “universal donor” blood
In: Biology
Type O negative blood has no antigens, it will not trigger an immune response, even if the recipient has a different blood type. As you might imagine, it’s a very popular resource on hospital shelves. That’s why O negative blood is in high demand yet in short supply.
ELI5: Different blood types have different antigens (proteins) and using a different blood that has a different type of antigen (protein) will cause issues. O- has no antigens and will cause no reactions. Positive (+) Rh blood can only be given to positive blood, negative (-) Rh blood can be given to either.
Also note the types of antigens are A and B. AB is both, O blood lacks A or B antigens.
https://www.redcrossblood.org/local-homepage/news/article/what-is-a-universal-blood-type-0.html
Blood has things in that not everyone can handle . Type A blood has A stuff in it. Type B has B stuff in it. So you can be type A, type B, or if you have both, Type AB. Type O has nothing unusual in it so it can be given to anyone.
The + or – is a third type of stuff. Plus means you have it, minus means you don’t. So O- blood has nothing at all unusual in it so it can safely be given to anyone. Type AB+ has everything unusual in it, so that blood can only be given to AB+ people.
In your blood, you can have things called antigens, either A, B, both (AB) or neither (O). Usually, Antigens trigger an immune response from your body, because they are what antibodies bind to to trigger their responses; however the body can recognize when the antigen is “self-made,” as in,,it knows the body makes the A antigen, so it doesn’t attack it.
This is a problem if you give blood with the A antigen to someone who doesn’t already produce the A antigen – since their body doesn’t produce it, they don’t know to ignore it, so it triggers an immune response. So rather than the patient getting blood that they need, their body sees the transfusion as a MASSIVE injection of foreign, dangerous material and attacks the blood, cause a myriad of issues and eventually death.
The negative is in reference to the Rh antigens system, another group of blood types, where negative means the lack of the D-antigen.
TLDR: there can be antigens in the blood, giving blood with antigens to someone who doesn’t normally have antigens will kill them. O- blood has none of the antigens, so can be given to anyone, while AB+ has all of them so can only be given to fellow AB+ people.
Basically there are three major antigens in blood that are really important for transfusions, and we call them A, B, and Rh. For each of these a person either has the antigen or they don’t. If you have A or B our blood notation lists A and/or B, and if you have Rh we list a +. If you don’t have A or B we use O in the notation, and if you don’t have Rh we use a -. So if someone has the A and Rh antigens, but not the B antigen, then their blood type is A+ (technically AO+, but we drop the O for ease of use).
For any of the three antigens if your body doesn’t have it already, then your body will negatively react to transfused blood with that type. If your body does have an antigen it can still accept blood that doesn’t have the antigen. O- blood doesn’t have any of the antigens, which means anyone can use that blood. Likewise AB+ blood has all 3 of the antigens, and can accept anyone else’s blood.
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