What blood type are you?

Photo by Jody Lane/American Red Cross

January is National Blood Donor Month, and the American Red Cross encourages everyone to contribute to this important work. Knowing your blood type is an important part of donating. There are different blood types because not all blood has the same kinds of red blood cells in it.

HOW CAN RED BLOOD CELLS BE DIFFERENT?

You’ve probably heard about blood types from your doctor (or at least your favorite television drama about doctors): A positive, O negative, etc. But what do these labels actually mean? Both the letter and the positive or negative symbol refer to antigens that either are or are not present on the surface of your red blood cells. A-type blood has A antigens, B-type blood has B antigens, AB has both, and O has neither. Whether your blood type is positive or negative depends on the presence or absence of another antigen called the Rh factor.

WHY IS BLOOD TYPE IMPORTANT?

Antigens are essential to how your body identifies and deals with infections. If a patient is given a blood transfusion of the wrong type, the body’s antigens will identify the donated blood as a harmful invader and activate the body’s immune system to reject it. This is why people with type O, which has neither A nor B antigens, can donate to anyone, but type A can only donate to others with type A. If you don’t know your blood type, ask your doctor for information so you can help those in need by donating blood.