ABO Incompatibility
A, B, and O are the three major blood types. The types are based on small substances (molecules) on the surface of the blood cells. When people who have one blood type receive blood from someone with a different blood type, it may cause their immune system to react. This is called ABO incompatibility. CAUSES. The different blood types are: *. Type A *. Type B *. Type AB *. Type O People who have one blood type may form proteins (antibodies) that cause their immune system to react against one or more of the other blood types. Being exposed to another type of blood can cause a reaction. This is important when a patient needs to receive blood (transfusion) or have an organ transplant. The blood types must be matched to avoid an ABO incompatibility reaction. For example: *. A patient with type A blood will react against type B or type AB blood. *. A patient with type B blood will react against type A or type AB blood. *. A patient with type O blood will react agains...