I am learning about different blood types and antigens associate with them. I am wondering--- why does the body reject blood types that contain foreign antigens? My teacher told me that there was a type of cells that are used in this response. I am not sure what she's talking about though. Also, how can blood rejection be a positive thing?

This site may help you.

http://nobelprize.org/educational_games/medicine/landsteiner/readmore.html

When it comes to blood transfusions, the body has a mechanism to recognize and react to foreign antigens. The immune system plays a crucial role in this process by producing specific proteins called antibodies, which are made by a type of white blood cell called B-lymphocytes.

These antibodies are part of the body's defense system and recognize foreign antigens as potential threats. In the case of blood transfusions, antigens on the surface of red blood cells are what the immune system recognizes. These antigens are classified into different blood types, such as A, B, AB, and O.

For example, if a person with blood type A receives blood from a person with blood type B, the recipient's immune system will recognize the B antigens as foreign. This triggers an immune response where the B-lymphocytes produce antibodies specifically designed to target and destroy the foreign antigens.

This immune response leads to the clumping or agglutination of red blood cells, causing a potentially dangerous reaction known as a transfusion reaction. Such a reaction can lead to a range of symptoms, including fever, chest pain, breathing difficulties, and in severe cases, kidney failure or even death.

Although blood rejection can have negative consequences, it can also be viewed as a positive thing. The body's ability to recognize and reject foreign antigens serves as a protective mechanism. It helps to prevent harmful substances or cells from entering the bloodstream and causing damage or infection. This is why compatibility testing is crucial prior to blood transfusions to ensure that the recipient receives compatible blood without triggering a transfusion reaction.

In summary, the body rejects blood types that contain foreign antigens due to the immune system's response to these antigens. The immune system produces antibodies that target and destroy foreign antigens, leading to a transfusion reaction. Blood rejection is a positive thing as it helps to protect the body from potential harm caused by foreign substances or cells entering the bloodstream.