A patient develops rapid graft swelling, cyanosis, and thrombosis within 30 minutes of renal transplant revascularization. Pre-existing donor-specific anti-HLA antibodies were present. This rejection is mediated by which mechanism?

• A CD8+ T-cell cytotoxicity against donor MHC class I
• B Macrophage activation by Th1 cytokines
• C Immune complex deposition in glomerular basement membrane
• D Preformed IgG antibodies activating complement on graft endothelium ✓

Explanation

Hyperacute rejection occurs within minutes to hours due to pre-existing donor-specific anti-HLA antibodies that bind graft endothelium, activate complement, and cause thrombosis and infarction. T-cell mediated rejection (acute cellular) occurs days to weeks later. Type IV hypersensitivity involves sensitized T cells, not preformed antibodies.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.