The pathogenic autoantibodies in Goodpasture syndrome target which structures?

• A. Glomerular basement membranes only
• B. Glomerular and alveolar basement membranes
• C. Hepatic basement membranes
• D. Vascular endothelium basement membranes

Answer: (B)

Autoantibodies in Goodpasture disease target the basement membranes of the kidney and lung. They bind to type IV collagen in glomerular basement membranes and alveolar basement membranes, especially the NC1 domain of the α3 chain. This causes inflammation and necrosis, leading to rapidly progressive glomerulonephritis and pulmonary hemorrhage. That’s why the lungs and kidneys are involved together. The liver’s basement membranes and vascular endothelium aren’t the targets, so hepatic involvement or isolated vascular processes aren’t typical. A key diagnostic clue is linear IgG deposition along the glomerular and alveolar basement membranes.