[Hepatic allograft rejection. Diagnostic and therapeutic aspects]

Rejection is still a major problem in liver transplantation: 50-70% of patients present at least one acute episode, while 5-15% develop chronic rejection. Acute rejection is suggested by clinical signs and abnormal laboratory test results, but only histological signs on biopsy specimens are adequately specific. The three most frequent elementary lesions are a portal infiltrate, bile duct alterations and endothelial inflammation. Several systems have been forwarded to classify the degree of rejection. Chronic rejection is characterized by a progressive reduction in the number of interlobular bile ducts. It does not respond to available immunosuppressive drugs and thus requires retransplantation. Prophylactic immunosuppression is usually based on the triple-drug combination cyclosporine/azathioprine/corticosteroids. The orthoclone OKT3 and FK506 have recently been proposed for prophylactic use in this setting. Treatment of liver graft recipients with cyclosporine carries a number of specific disadvantages, particularly with regard to gastrointestinal interactions (delayed intestinal absorption in patients with cholestasis, bile derivation, diarrhea or receiving cholestyramine; possibility of a sharp increase in blood cyclosporine levels when the Kehr drain is clamped), and drug interactions (cyclosporine metabolization of CP450-IIIA accounts for most such interactions). The results of radioimmunoassay and TDx must be interpreted with care, and HPLC remains the reference technique in borderline cases. Cyclosporine is hepatotoxic in about 20% of cases, generally giving rise to cholestasis. This toxicity is dose-dependent and therefore diminishes when the dosage is reduced. Most groups initially treat rejection with corticosteroids. The response to treatment is generally evaluated in terms of liver function tests.(ABSTRACT TRUNCATED AT 250 WORDS)