REACTIVATION OF HEPATITIS-B AFTER CHLOROQUINE WITHDRAWAL

A severe flare-up of chronic hepatitis B infection with liver cell ins ufficiency has been observed in two patients after discontinuation of chloroquine administered either as malaria prophylaxis or as treatment of presumed rheumatoid arthritis. Chloroquine is known to inhibit the association of the major histocompatibility complex type II with hepa titis B virus antigens, thereby inhibiting T-cell mediated lysis of in fected cells. Furthermore, it inhibits uptake of duck hepatitis B viru s by duck liver cells. These in vitro studies and our clinical observa tions suggest that chloroquine inhibits lysis of hepatitis B virus inf ected hepatocytes. Withdrawal of chloroquine in patients with chronic hepatitis B virus infection can lead to a rebound immune response mani festing as a reactivation of hepatitis B, similar to that observed aft er steroid withdrawal.