Autoimmune disease is a condition in which the body’s immune system mistakenly attacks the body itself. The immune system naturally defends the body against pathogens such as bacteria and viruses. When he notices the presence of these alien invaders, he sends an army of fighter cells to attack them. Normally, the immune system can distinguish between foreign cells and self-cells. In an autoimmune disease, the immune system considers a part of the body, such as joints or skin, to be foreign and releases proteins called antibodies to attack healthy cells. Some autoimmune diseases attack only one tissue. Doctors still don’t know what actually causes the immune system to go wrong. However, some people are more likely than others to develop an autoimmune disease. According to research conducted in 2014, women suffer from autoimmune disease twice as often as men, and most of the disease occurs during women’s reproductive years. Also, some types of autoimmune diseases are common among certain groups.