ABO and the most common blood types

ABO and the most common blood types 

The ABO blood group system classifies blood types according to the different types of antigens in the red blood cells and antibodies in the plasma. 

They use the ABO system alongside the RhD antigen status to determine which blood type or types will match for a safe red blood cell transfusion. 

There are four ABO groups: 

Group A: The surface of the red blood cells contains A antigen, and the plasma has anti-B antibody. Anti-B antibody would attack blood cells that contain B antigen.

Group B: The surface of the red blood cells contains B antigen, and the plasma has anti-A antibody. Anti-A antibody would attack blood cells that contain A antigen. 

Group AB: The red blood cells have both A and B antigens, but the plasma does not contain anti-A or anti-B antibodies. Individuals with type AB can receive any ABO blood type. 

Group O: The plasma contains both anti-A and anti-B antibodies, but the surface of the red blood cells does not contain any A or B antigens. Since these antigens are not present, a person with any ABO blood type can receive this type of blood. 

Rhesus factor 

Some red blood cells have Rh factor, also known as the RhD antigen. Rhesus grouping adds another dimension. If the red blood cells contain the RhD antigen, they are RhD positive.

If they do not, they are RhD negative.

Understanding ABO and Rhesus 

Doctors need to take into account both ABO and Rh when considering blood types. This means there are eight main blood types in the ABO/Rh blood group system.

Universal donor and universal recipient

O negative blood contains no A, B, or RhD antigens. Almost anyone with any blood type can receive these red blood cells. A person with group O negative blood is a universal donor.

• A person with O-negative blood can donate to almost anyone.
• A person with Rh-negative blood can donate to a person with Rh-negative or Rh-positive blood.
• A person with Rh-positive blood can only donate to someone with Rh-positive blood.

As a result, there is a high demand for O negative blood.

The rules for plasma are the opposite of those for Rh. A universal plasma donor will have type AB blood.