Type II
This type of hypersensitivity reaction is mediated by IgM and IgG antibodies. This reaction is called a cytotoxic allergic reaction because these antibodies damage cells in the body by binding to the cells and activating a chain of events known as a complement. There are two types of cytotoxic hypersensitivities. These are hemolytic transfusion reactions and hemolytic disease of newborns.
Hemolytic transfusion reactions involve incompatible blood types [3]. This reaction is common during blood transfusions when a person is given a different blood type. If you have blood type B and receive a transfusion of blood type A, antibodies in your system will bind to A antigens on your donor’s blood and destroy them. The destroyed cells can block important vessels and cause organ damage or death.
Hemolytic disease of newborns is similar to a hemolytic transfusion reaction, but it involves Rhesus (Rh) incompatibility [4]. An Rh-negative woman pregnant with an Rh-positive child for the first time will build up antibodies against Rh antigens. During subsequent pregnancies, these antibodies will destroy the blood cells of Rh+ babies unless the mother is given Rhogam injections to stop these antibodies from forming.