9The Importance of Knowing Blood Types
The immune system contains antibodies, which target bacteria and viruses to protect the body. However, they also attack other antigens that are not part of your blood type. If people with type B get type A blood in a transfusion, the antibodies would damage blood cells containing the A antigens. This would lead to dangerous complications. Overall, people with AB blood may receive type A or type B blood. Those with O blood are called universal donors as they may give blood to people with any blood type. [9]
