The hypersensitivity type in SLE (Systemic Lupus Erythematosus) is:

Correct answer: C. Type III (immune complex-mediated)

• A. Type IV is T-cell mediated (contact dermatitis, TB skin test, transplant rejection) — not the immune complex mechanism of SLE.
• B. Type I is IgE-mediated, causing immediate hypersensitivity (anaphylaxis, atopy, asthma) — NOT the mechanism of SLE.
• C. SLE is the classic example of TYPE III HYPERSENSITIVITY (immune complex-mediated). In SLE, the patient produces autoantibodies (anti-dsDNA, anti-Smith, anti-histone) that form IMMUNE COMPLEXES with their antigens. These immune complexes deposit in vessel walls, glomeruli (lupus nephritis), joints, and skin, activating complement and causing inflammation. Key lab: ANA (antinuclear antibody) positive; anti-dsDNA positive in SLE.
• D. Type II involves antibody-mediated cytotoxicity (e.g., Goodpasture's, pemphigus, autoimmune hemolytic anemia) — not the primary mechanism of SLE.