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What is a blood type?
When we talk about blood type, we are usually referring to the typing of red cells. We are looking for the presence or absence of the A or B antigen, and the Rh (or D) antigen. The A and B antigens are protein molecules found on the surface of the red cell. If you are type O, you lack both the A and the B antigen. These are the most common antigens. In addition, there are nearly 600 other red cell antigens.
Percentage of Americans with your blood type...
This chart reflects blood types of U.S. Caucasions.
Why is blood typing important?
When our bodies are exposed to something foreign, like a blood transfusion, our immune system responds to protect us. One weapon the body uses is the production of antibodies. Antibodies are protein molecules that are released by plasma cells and bind to a specific antigen. The antibodies couple with the antigens on the surface of the invading cells and try to destroy the cells. We crossmatch a donor's blood with a patient's blood to prevent this kind of reaction, which can range from mild to very serious. Antigens are also found on the surface of white cells and platelets.
What is alloimunization?
Those of us who need blood may only need it at one time during our lives, either to help overcome a disease, because of an injury or to replace lost blood in surgery. But some patients, like sickle cell disease patients, need blood many times during their lives. If the blood they receive is not a very close match, they can begin to develop antibodies against the donated blood. This process is called alloimunization. To prevent alloimmunization, blood for these patients must be closely matched. Often, this will mean testing blood samples from many blood donors in order to find a match. For African-American sickle cell disease patients, the best match will most often come from donors of African descent. Fully one third of requests for rare blood received by the Red Cross are for blood types found almost exclusively among African Americans.
What is a rare blood type?
Some patients require rare blood types found in only one in 1,000 donors, or even less frequently. Through the American Rare Donor Program we identify donors who have these rare blood types and ask them to let us list them in our registry. When a need for their special blood type arises, we can call upon this donor to give. Red Cross also freezes some rare units of red cells, which can be stored for up to ten years, to assure their availability in time of need.
If you are asked to join this registry, please say yes. Someone, somewhere needs the blood that you, and only you, may be able to give. Rare blood may be sent anywhere in the world to help a patient.
What is the universal donor?
Type O donors are known as universal donors because their red blood cells may be transfused to patients of any other blood type in an emergency situation or if the needed blood type is unavailable. Because any patient can receive O negative red blood cells, there is a need for O donors to give more often and shortages of type O blood are very serious. Type AB plasma can be given to anyone as well. But whatever your blood type, your blood is important to someone! |
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