For an organ transplant, it is an advantage to have an identical twin. Why?

Transplantation is the procedure of replacing the unhealthy organ with a healthy one in an individual. Sometimes these replaced organs get rejected by the body’s immune system as they are considered as a foreign object by the body. In response to this, cell mediated immune response takes place by T-Lymphocytes. These lymphocytes try to differentiate between self cells and foreign cells because of which sometimes the graft gets rejected. To avoid this, blood groups and tissue matching is done. In the case of identical twins the chances of graft rejection is less because blood group and tissue match is easy.