Autoantibodies against which basement membrane component characterize Goodpasture syndrome?

• A. Type IV collagen
• B. Type I collagen
• C. Laminin
• D. Elastin

Answer: (A)

Autoantibodies in Goodpasture syndrome target a basement membrane component, specifically type IV collagen, which forms the network structure of glomerular and alveolar basement membranes. The autoimmune attack is focused on the NC1 domain of the alpha-3 chain of type IV collagen, leading to linear IgG deposition along these membranes and resulting in rapid nephritis and pulmonary hemorrhage. Other options don’t fit because Type I collagen is a fibrillar collagen in interstitial tissues (not basement membranes), laminin is a basement membrane glycoprotein but is not the primary autoantigen in this condition, and elastin is an elastic fiber component, not a basement membrane constituent.