Pathophysiology
Clinical meaning
Systemic lupus erythematosus (SLE) is a chronic multisystem autoimmune disease characterized by production of autoantibodies against nuclear antigens (anti-nuclear antibodies/ANA, anti-double-stranded DNA, anti-Smith), leading to immune complex deposition and inflammation in virtually any organ system. The exact cause involves genetic predisposition, environmental triggers (UV light, infections, medications), and hormonal factors (10:1 female-to-male ratio, most common in women of childbearing age). Immune complex deposition in the kidneys causes lupus nephritis (most serious common complication), in joints causing non-erosive arthritis, in skin causing the classic malar (butterfly) rash, and in serous membranes causing pleuritis and pericarditis. Complement levels (C3, C4) decrease during active disease as complement is consumed. The disease follows a relapsing-remitting pattern with flares triggered by UV exposure, infection, stress, and medication changes.