Transplant Rejection

A 35-year-old man receives a living-related kidney transplant from his HLA-identical brother. On postoperative day 5, he develops fever (38.5°C), rising serum creatinine (2.8 mg/dL, baseline 1.0 mg/dL), and oliguria. Ultrasound shows increased echogenicity of the graft with normal perfusion on Doppler. Renal biopsy reveals interstitial infiltration by mononuclear cells with tubulitis and glomerulitis. Direct immunofluorescence is negative for immunoglobulin and complement deposition. What is the most likely diagnosis?

A 52-year-old woman undergoes deceased-donor heart transplantation. Intraoperatively, the donor heart develops severe cyanosis, becomes flaccid, and shows poor contractility within minutes of reperfusion. Angiography reveals no coronary artery disease. Serum complement levels are low. A biopsy of the graft shows neutrophilic infiltration with endothelial necrosis and fibrin deposition in coronary vessels. What is the most likely diagnosis?

Which type of transplant rejection is mediated primarily by CD8+ cytotoxic T lymphocytes recognizing donor MHC class I antigens?

Hyperacute transplant rejection occurs within minutes to hours and is prevented by which pre-transplant immunological test?