What if a person with type A blood donates to B blood?

A person with type A blood cannot donate to someone with type B blood because the recipient's immune system would attack the donor's A antigens. This could lead to a serious condition called hemolytic transfusion reaction, in which the recipient's red blood cells are destroyed.

Here's a more detailed explanation of what would happen:

* When type A blood is transfused into a person with type B blood, the recipient's immune system recognizes the A antigens on the donor's red blood cells as foreign.

* The recipient's immune system produces antibodies against the A antigens. These antibodies are called anti-A antibodies.

* The anti-A antibodies bind to the A antigens on the donor's red blood cells, causing them to clump together. This process is called agglutination.

* The agglutinated red blood cells can block blood vessels, which can lead to tissue damage and organ failure.

* Hemolytic transfusion reaction can be a life-threatening condition.

For these reasons, it is important to make sure that blood transfusions are only given between people with compatible blood types.