The human body contains around 8 to 10 pints of blood depending on the size of the individual. However, the composition of the blood is not the same in each person. This is what makes the person’s blood type.
An individual’s blood type depends on which genes were passed on by their mother or father.
The best-known way of grouping of blood types is the ABO system, although there are other groups.
Within the ABO group, four major categories are divided into eight common blood types: A, B, O, and AB.
Over 9.5 million people in the United States (U.S.) are blood donors, and around 5 million patients receive blood each year, according to the Centers for Disease Control and Prevention (CDC).
It is crucial to give a patient the right blood type in a transfusion. The wrong type can trigger an adverse and potentially fatal reaction.
What makes a blood type?
The ABO system is the most familiar way of grouping human blood types.
Blood consists of cells and a yellow watery liquid known as plasma. The blood group depends on what each part of the blood contains.
The two main blood group systems are ABO antigens and Rhesus antigens (including RhD antigen). These two antigens are used to classify blood types.
Bacteria and viruses normally carry an antigen. During an infection, their antigen marks them as something that is foreign to the body or not usually found in the body.
Most red blood cell antigens are protein molecules found on the surface of red blood cells.
White blood cells produce antibodies as an immune defense. These antibodies will target antigens and attack the foreign object, for example, the bacteria.
Cross-matching of blood types is vital. If a person receives red blood cells with antigens not normally present in their system, their body will reject and attack the new red blood cells.
This can cause a severe, and possibly life-threatening reaction.
The eight main blood types are A, B, O, or AB, and each type can be positive or negative.
A-positive (A+) occurs in 30 percent of people in the U.S.
A-negative (A-) occurs in 6 percent of people
B-positive (B+) occurs in 9 percent of people
B-negative (B-) occurs in 2 percent of people
AB-positive (AB+) occurs in 4 percent of people
AB-negative (AB-) occurs in 1 percent of people
O-positive (O+) occurs in 39 percent of people
O-negative (O-) occurs in 9 percent of people