A 47-year-old man with a history of chronic renal failure presents to the clinic for a follow up after a kidney transplant three weeks ago. His surgery was successful and his transplanted kidney started producing urine right after the operation. However, today his urine output drops and his serum creatinine begins to rise. There is no fever or dysuria. Urinalysis shows no abnormality. Biopsy from the transplanted kidney shows cellular infiltrate of cytotoxic cells (CD8).
What is the most likely diagnosis of this condition?