A patient post-liver transplant develops organ rejection with lymphocyte infiltration and bile duct epithelial apoptosis. The mechanism of T-cell-mediated bile duct injury involves primarily:
- A Antibody-dependent cellular cytotoxicity by NK cells via FcγRIII
- B Complement cascade activation depositing MAC on bile duct membranes
- C Perforin/granzyme B pathway by CD8+ cytotoxic T-lymphocytes recognizing allogeneic HLA class I on biliary epithelium ✓
- D Delayed hypersensitivity with neutrophil-mediated oxidative damage to bile duct
Correct answer: C. Perforin/granzyme B pathway by CD8+ cytotoxic T-lymphocytes recognizing allogeneic HLA class I on biliary epithelium
Explanation
In T-cell-mediated (acute cellular) allograft rejection, donor-specific CD8+ cytotoxic T lymphocytes recognize alloantigens presented on HLA class I molecules of biliary epithelial cells and hepatocytes. They deploy perforin to create membrane pores and deliver granzyme B which activates procaspase-3 and -8 in target cells, triggering apoptosis. This bile duct epithelial apoptosis (ductopenia in chronic rejection) is the hallmark histological finding. ADCC by NK cells and complement-mediated injury characterize antibody-mediated rejection.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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