Causes of autoimmune disease Autoimmune disease often occurs in the elderly. Occurs when an individual begins to make antibodies against or cytotoxic cells against normal body cells. Causes of autoimmune diseases ? Environmental factors such as viral. ? Fetal cell may cross placenta and trigger autoimmune response in pregnant women. ? Genetic factors such as certain MHC genes. ? Failure of the normal control mechanisms of the immune system. Examples of Autoimmune disease hemolytic anemia- individual produces antibodies which act against body red blood cells. Causes severe anemia. Autoimmune disease develops against cells in the pancreas or thyroid gland. Can cause destructions of the gland and deficiency.