Type B with B antigens on the red cells and anti-A antibodies in. Also note that blood group compatibilities are reversed for plasma transfusions. The ABO System Type A with A antigens on the red cells and anti-B antibodies in the plasma. Click on a blood type below to learn more.

The presence or absence of the Rh antigen determines whether we are (+) or (-). The least common blood types are B- and AB-. In addition to the A and B antigens, there is a protein called the Rh factor, which can be either present (+) or absent (), creating the 8 most common blood types ( A+, A-, B+, B-, O+, O-, AB+, AB- ). The majority of people in any geographical region are Rh positive. The two most important ones are ABO system antigens and the Rh system. People have molecules called antigens on the surface of their red blood cells. It is the most common blood type among Australian Aborigines, Celts, those living in Western Europe, and in the United States. Our interactive blood group calculator determines a baby's probable blood types for the ABO system based on the parents' blood type and vice versa. The A and B antigens, and their presence on our red blood cells determines if our blood type is O (lacks both A and B antigens), A (has the A antigen only), B (has the B antigen only), or AB (has both A and B antigens). The O blood type is the most common around the globe and is carried by nearly 100 of those living in South America. While there are many different types of antigens on our red blood cells and throughout our body, there are 2 main blood antigen groups that determine our blood type: ABO and Rh. Our body produces antibodies (part of our immune response) against antigens that are “foreign” to our body – thus limiting the blood types that patients can receive for transfusion. These antigens are an important part of blood donation and transfusion because patients cannot receive red blood cell transfusions from donors that have different antigens than their own red blood cells.

Our different blood types are determined by the presence or absence of certain antigens (unique substances) on the surface of our red blood cells.

Blood type