In renal transplantation, hyperacute rejection occurs within minutes to hours of graft reperfusion. The underlying mechanism is:

• A T-cell mediated cellular cytotoxicity against donor MHC class I antigens
• B Natural killer cell-mediated antibody-dependent cytotoxicity
• C Cytokine storm from regulatory T-cell exhaustion
• D Pre-formed recipient antibodies against donor ABO or HLA antigens activating complement ✓

Explanation

Hyperacute rejection is caused by pre-formed recipient antibodies against donor ABO blood group antigens or HLA antigens (detected by a positive pre-transplant crossmatch). Upon reperfusion, antibodies bind to graft endothelium, activate complement (classical pathway), leading to endothelial damage, intravascular thrombosis, and immediate graft loss. This is now rare due to pre-transplant crossmatch testing and ABO compatibility. Acute cellular rejection occurs days to weeks post-transplant via T-cell mechanisms.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.