Why blood type ab cant donate to the other type?

Blood type AB can donate to people with blood type AB only. This is because AB plasma contains both anti-A and anti-B antibodies, which would cause a transfusion reaction if transfused into someone with A, B, or O blood.

Here's a more detailed explanation:

* Blood type AB plasma contains anti-A and anti-B antibodies. These antibodies are proteins that recognize and attack foreign substances in the body. In the case of blood type AB, the anti-A antibodies will attack blood cells that have the A antigen (found in blood types A and AB) and the anti-B antibodies will attack blood cells that have the B antigen (found in blood types B and AB).

* If someone with blood type AB donates blood to someone with A, B, or O blood, the recipient's immune system will attack the donated blood cells. This is because the recipient's plasma contains antibodies that are specific for the antigens on the donated blood cells. For example, if someone with blood type A receives blood from someone with blood type AB, the recipient's anti-B antibodies will attack the donated B blood cells.

* The transfusion reaction can cause a variety of symptoms, including fever, chills, nausea, vomiting, and difficulty breathing. In severe cases, a transfusion reaction can even be fatal.

For these reasons, people with blood type AB can only donate blood to other people with blood type AB.