Which abnormality initiates the immune complex formation responsible for IgA nephropathy?

• A Galactose-deficient IgA1 recognized by antiglycan autoantibodies ✓
• B Antibodies against the NC1 domain of collagen IV alpha3 chain
• C Autoantibodies directed against the M-type phospholipase A2 receptor
• D Immune complexes containing hepatitis B surface antigen

Explanation

In IgA nephropathy, mucosal plasma cells produce IgA1 with deficient galactosylation of O-linked glycans in its hinge region. These galactose-deficient IgA1 molecules are recognized by circulating autoantibodies, generating large immune complexes that deposit in the glomerular mesangium and activate the alternative complement pathway. The NC1 domain target defines anti-GBM disease and the PLA2R target defines primary membranous nephropathy.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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