Matching a donor's blood and a patient's blood is critical in transfusions. If someone with type A+ blood receives type AB+, he may have a severe hemolytic reaction. This can destroy many of his red cells and quickly kill him. While blood-typing and cross matching are now routine, errors do occur. Every year people die of hemolytic reactions. this is because persons with AB+ blood type can only give blood to person of the same blood type (AB+) but can receive blood from everyone. another way to put this is that person with A+ blood type can only receive blood from persons with blood types of A+ A- O+ O- . A+ blood type people can give blood to AB+ but not vice versa. giving blood from an AB+ donor to an A+ recipient could result in clumps within the blood vessel, producing a fatal result.
