What does blood type mean?

Answer 1

When an individual has type AB blood, it means the surface of their blood cells contain both A and B antigenic markers. A person with AB blood does not produce antibodies against either of these markers, thus their body does not mount an immune response against their own blood cells.

A and B are two distinct antigenic markers/targets that antibodies can attack. Humans can have either A, B, both AB or neither A or B antigens. Your blood type designates the antigen your cells display. Since your body tolerates the type of blood you have, your body will not produce antibodies against your own blood type (otherwise you would be dead as your immune system would mount an attack on your own blood). However, your body will produce antibodies against the other antigenic markers that you do NOT normally exhibit. For example, a type B individual (who produces anti-A antibodies because they are not supposed to have type A blood cells in their body) cannot accept type A blood, otherwise their anti-A antibodies would attack the blood cells leading to immunorejection.

An individual with type O blood has neither A or B antigens on the surface of their blood cells and thus can donate this blood to any other individual, since the blood will not be attacked by antibodies that target either A or B antigens. O is thus the universal donor, while AB is the opposite and is the universal acceptor as it tolerates both A and B antigens.

Your body produces antibodies against anything it intends to attack, such as viruses, bacteria, and other foreign particles. The agent your body produces that does the attacking is called an antiBODY. The thing that gets attacked by an antibody is an antiGEN.