WHAT CAUSES BLOOD GROUPS TO BE DIFFERENT?
Your blood group is determined by the presence or absence of two antigens that are attached to your red blood cells:
-
Type A antigens
-
Type B antigens
Antigens are generally defined as 'toxic substances' that enter your body and cause harm. However, there are also antigens that we inherit from our parents, most of which are harmless, e.g., blood type antigens. The blood type antigens you do (or do not) inherit from your parents will determine your blood group:
People with group A blood have only inherited type A antigens
People with group B blood have only inherited type B antigens
People with group AB blood have inherited both type A and B antigens
People with group O blood have not inherited either type A or B antigens from their parents
If an antigen enters your body that is not usually there, your body will initiate an immune response to destroy it. Antibodies are the molecules that will be released as part of this immune response to destroy any 'foreign' antigens.
There are two antibodies in the blood that will attack the antigens on red blood cells:
-
Anti-A antibodies will attack the type A antigen
Type A antigens are regarded as 'foreign' by anti-A antibodies. This means that if someone has anti-A antibodies in their blood, they will attach to type A antigens on the red blood cells and destroy them.
-
Anti-B antibodies will attack the type B antigen
Type B antigens are regarded as 'foreign' by anti-B antibodies. This means that if someone has anti-B antibodies in their blood, they will attach to type B antigens on the red blood cells and destroy them.
