In an autoimmune illness like rheumatoid arthritis, what does the body’s system do?

In autoimmune illnesses such as rheumatoid arthritis, the body's immune system mistakenly identifies its own normal tissues as foreign and potentially harmful, leading it to attack these tissues. This aberrant immune response causes inflammation and damage primarily to the joints, but can also affect other systems in the body. In rheumatoid arthritis, the immune system targets the synovium (the lining of the joints), leading to pain, swelling, and eventually joint erosion. Unlike a typical immune response that works to protect the body against harmful invaders like bacteria or viruses, in an autoimmune condition, the immune system's misguided actions can result in significant harm to the body itself. Understanding this concept is crucial when discussing the pathology and treatment options for autoimmune diseases.