Autoimmune Disease

An autoimmune disease is a disorder in which immune responses directed against the body’s own molecules, cells, or tissues contribute to pathological damage or dysfunction. Normally, the immune system maintains self-tolerance through mechanisms that limit harmful responses against the body’s own components. Autoimmune disease develops when these controls are sufficiently disrupted for autoreactive immune responses to become pathogenic .^1,2

The adaptive immune system is central to many autoimmune diseases. Self-reactive T cells can recognize the body’s own antigens and promote inflammation or directly damage cells, while self-reactive B cells can produce antibodies against self-antigens, called autoantibodies. Different autoimmune diseases involve different combinations of these mechanisms, together with inflammatory signals from the innate immune system .^1,2,3

Autoimmune diseases can primarily affect a particular organ or can involve multiple tissues. Type 1 diabetes, for example, is characterized by immune-mediated destruction of pancreatic beta cells, whereas systemic lupus erythematosus can affect many organ systems. Susceptibility generally reflects interactions among immune-regulatory mechanisms, genetic factors, and environmental influences rather than a single universal cause shared by all autoimmune diseases .^1,3

Autoimmunity is not identical to autoimmune disease. Self-reactive immune cells or autoantibodies can sometimes be detected without causing clinical disease. The term autoimmune disease is used when autoimmune processes contribute to a pathological condition. Autoimmune disease is also distinct from autoinflammatory disease, in which dysregulation of innate immunity rather than self-specific adaptive immune responses is the predominant mechanism, although the boundary between these categories is not always sharp .¹