Generally speaking, an autoimmune diseases are conditions in which your immune system mistakenly attacks the cells and organs within your own body. Typically, the immune system will guard against germs like bacteria and viruses, and will know the difference between your cells and the foreign cells. When it senses these foreign invaders, it sends out fighter cells to attack them. With autoimmune diseases, the immune system mistakes part of your body, like your joints or skin, or even your organs as foreign, therefore it releases proteins called autoantibodies that end up attacking healthy cells. Some autoimmune diseases target only one organ, such as type 1 diabetes which damages the pancreas. Other diseases, like systemic lupus erythematosus (SLE), will often affect the entire body. Even today, doctors are not entirely certain as to what causes the immune-system misfires. And yet, some people are more likely to get an autoimmune disease than others.