Autoimmunitet

Autoimmunitet, also known as autoimmunity, is a state in which the immune system mounts a response against self-tissues. Normally, immune tolerance prevents self-reactive cells from attacking healthy cells. In autoimmunity, this tolerance fails, leading to self-directed inflammation and tissue damage. Autoimmune diseases can be organ-specific, affecting a single tissue or organ, or systemic, involving multiple organs.

Pathogenesis is multifactorial. Genetic factors, especially certain HLA alleles, confer susceptibility. Environmental triggers such as infections, drugs, or toxins may initiate or accelerate disease in predisposed individuals. Mechanisms include production of autoantibodies by B cells and activation of autoreactive T cells. Processes like molecular mimicry, epitope spreading, and bystander activation may link infections to autoimmunity. The immune system's regulation, including regulatory T cells and cytokine networks, may be impaired.

Common organ-specific diseases include type 1 diabetes, autoimmune thyroid diseases (Hashimoto's, Graves'), and myasthenia gravis. Systemic diseases include SLE, rheumatoid arthritis, scleroderma, and vasculitides, affecting skin, joints, kidneys, nerves, and other organs.

Diagnosis combines clinical features with autoantibody testing (ANA, anti-dsDNA, anti-Smith, anti-TPO, RF, ANCA) and imaging or biopsy as needed. Exclusion of other causes is essential.

Treatment aims to suppress abnormal immune activity and manage symptoms. Options include corticosteroids, conventional DMARDs (methotrexate, azathioprine), biologics (rituximab, TNF inhibitors), and targeted therapies, along with organ-supportive care. Research continues into better understanding triggers, diagnostics, and personalized therapies.