O- “universal donor” blood
In: Biology
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.
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