Human blood was first classified into 4 well-known types in the first decade of the 1900s by Karl Landsteiner, an Austrian physician. It’s no secret that it’s important to know one’s blood type for emergency situations, as a blood match is crucial for safe transfusions. It turns out, however, that blood characteristics can also influence our health, and, as some people believe, our fortune and personality as well.
1. How are blood types determined?
Blood types, or blood groups, are classified according to the presence or absence of certain antigens that can trigger an immune response when they are foreign to the body. These antigens can make the immune system of the patient attack the transfused blood. This is why it is so important to know your blood type and to be aware of the safe matches for blood transfusions.
2. Type O blood characteristics
There are 4 main blood types determined by the presence or absence of A and B antigens in the red cells’ surface and A and B antibodies in the plasma. In addition to the A and B antigens, there is a protein called Rh factor which can be either present or absent. Altogether, this makes up 8 blood types: A+, A-, B+, B-, O+, O-, AB+ and AB-. Type O blood has neither A nor B antigens in the red blood cells but has both A and B antibodies in the plasma. Type O+ is the most common blood type which accounts for 37% — 53% of people in different ethnic and racial groups.
3. People with type O blood are universal donors.
People with type O+ blood can donate their blood to all 4 groups, but only to people with the RH positive subgroup (O+, A+, B+, AB+). Red cells of O- type can be transfused to all 8 subgroups, which makes it a universal blood type that is always needed for emergency transfusions. Type O- blood is transfused in emergency cases when it is important to save the life of a patient before the crossmatch test is completed. What’s more, is type O- blood is the safest for newborn babies whose immune systems are under-developed.
4. Type O blood individuals can receive type O blood only.
People with type O+ blood can receive blood from people with both O+ and O- types, while those who have type O- blood can only receive the same O- type blood. In emergency cases when type O- blood is in short supply, it can be substituted with type O+ blood.