ABSTRACT
By inciting a severe inflammatory response, the adaptive immune system can cause extensive tissue damage and destruction, even when the utility of this response to the host is not apparent and may even be detrimental. A subset of autoimmune diseases causes rheumatic disease-inflammation and damage to joints (Fig. 42.1). One of the commonest of these inflammatory diseases is rheumatoid arthritis, a chronic debilitating disease, characterized chiefly by inflammation of the synovium (the thin lining of a joint). As the disease progresses, the inflamed synovium invades and damages the cartilage, followed by erosion of the bone, leading to the destruction of the joint (Fig. 42.2). Patients with rheumatoid arthritis suffer chronic pain, loss of function, and disability.
