system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 What will happen if you get the wrong bloodtype in you?
gpt
Basically, your immune system sees the new blood cells that you’re being given as invaders and they immediately begin attacking. Your own white blood cells begin destroying the new red blood cells - this is called hemolysis.

Doesn’t sound too bad, right? You’re no worse off, the transfusion just didn’t help because the new red cells got destroyed.

Wrong. It’s very bad.

The new red cells are destroyed and all the stuff they carried around in their guts is immediately released into your body. Now, your body can handle some destroyed red blood cells, it does this all the time. But your body can’t handle the enormous amount of destroyed cell guts that are released all at once.

Your liver and kidneys are left to pick up and filter out all these destroyed red cells, which is bad enough. But worse yet, those destroyed cells can cause platelets to start going all wacky as other complicated parts of your immune system are triggered by this entire fiasco, and those triggered platelets start sticking together and your blood clots rapidly and inappropriately. That clotting could end up killing you.

Even creepier is that it’s been said that you have a “sense of impending doom” before shit gets real wild. So you know you’re going to die even before your body starts dying.