Question: I am currently wondering about the human body the heart is the engine of the human body said by unusual means you need a blood transfution is it possible for the body to reject it thus killing you?

Mike Dodd answered on 15 Jun 2011:

Hey Diddycoy, nice question. I guess there are two parts really. Firstly, blood transfusions. You might need a blood transfusion due to an accident, like a car crash, or because you are having an operation. You normally have 8 pints of blood in your body and you need to replace this if you lose too much. Everyone has a blood type, there are only a few blood types, A, B, AB and O. Also you can have negative and positive, so I’m O positive. When you give blood, they remove the immune cells (called white blood cells) out of your blood, this lowers the chances that the blood will be rejected and would possibly kill you. You need to match blood types between donor (the person how gave the blood) and patient (injured person). This means that I would need O positive blood. As long as these are matched the blood won’t be rejected by the body and you will live after a blood transfusion.

Secondly, heart rejection. People that have had a heart attack or have had heart failure for a long time, might need to have a heart transplant. Heart failure is where you heart has been injured and can no longer pump blood properly around your body. There are over 68,000 new people with heart failure every year in the UK. A heart transplant is the last option. This is because replacing the heart is very difficult, you have to reconnect major blood vessels and hope they hold for many years. As the heart beats 100,000 times a day, it need to be tough and any reconnecting of hearts needs to hold. The other problem is rejection. If you simply put a new heart into somebody, it would be rejected very quickly and they would die. This is because on the surface of every cell in your body, there is a unique pattern of proteins and sugars. This is designed, so that if you get an infection, this pattern changes, and the body knows that there is a virus or infection. Normally the immune system (white blood cells) would kill this cell and any others with this “new” pattern. So the cells on the surface of the new heart would have a different pattern, to the patients body and would be killed by the immune system. So after a heart transplant, the patient is given immunosuppression drugs, which turn your immune system off and the new heart can live happily in it’s new body. Hope that was what you were after. Thanks