A 38-year-old woman with a known history of autoimmune hepatitis is admitted with jaundice, pruritus, and right upper quadrant pain. Liver function tests show ALT 1200 U/L, AST 1100 U/L, alkaline phosphatase 320 U/L, and total bilirubin 8.2 mg/dL. Abdominal ultrasound reveals hepatomegaly with increased echogenicity. A liver biopsy is performed, which shows hepatocyte swelling with intact cell membranes, preserved nuclei, and cytoplasmic rarefaction. Electron microscopy demonstrates dilated rough endoplasmic reticulum (RER) and mitochondria with intact cristae. The patient is started on high-dose corticosteroids and azathioprine. Two weeks later, her liver enzymes normalize and jaundice resolves. Which of the following best explains the reversibility of hepatocyte injury in this patient?