Immunology USMLE Step 1 Practice Question
A 52-year-old man with end-stage renal disease undergoes kidney transplantation. Within minutes, the graft becomes cyanotic and stops producing urine. Vital signs show BP 158/92 mmHg, HR 110/min, RR 20/min, temp 37.2°C. Doppler ultrasound reveals absent diastolic flow in renal vasculature. Graft biopsy demonstrates widespread thrombosis of vessels with fibrinoid necrosis and complement deposition. Serologic testing for donor-specific antibodies is pending. He denies previous transfusions. Which immunologic mechanism most likely caused this hyperacute rejection?
Answer choices
- ARecipient CD8 positive T cells reacting against donor MHC weeks after transplant
- BImmune complex deposition following exposure to foreign serum proteins
- CChronic cytokine driven smooth muscle proliferation causing graft arteriosclerosis
- DProliferation of donor T cells in an immunocompromised host
- EPreexisting recipient antibodies against donor antigens activating complementCorrect answer
- FNK cell-mediated antibody-dependent cellular cytotoxicity against donor endothelial cells
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