Alloimmunity is an immune response to foreign antigens (alloantigens) from members of the same species. The body attacks mainly transplanted tissue and even the fetus in some cases. Alloimmune response results in graft rejection, which is manifested as deterioration or complete loss of graft function. In contrast, autoimmunity is an immune response to the self's own proteins. (The allo- prefix means "other", whereas the auto- prefix means "self".)