Stimulation of Suicidal Erythrocyte Death by Ribavirin

Ribavirin is widely used in the treatment for viral disease such as chronic viral hepatitis. Side effects limiting the use of the drug include haemolytic anaemia. If challenged by stimulators of haemolysis, erythrocytes may enter suicidal death or eryptosis, thus preventing the release of haemoglobin into circulating blood. Eryptosis is characterized by cell shrinkage and by cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. Eryptosis may be triggered by increase in cytosolic Ca2+ activity ([Ca2+](i)). This study explored whether ribavirin modifies [Ca2+](i) and elicits eryptosis. Cell volume has been estimated from forward scatter, phosphatidylserine abundance at the erythrocyte surface from annexin V binding, haemolysis from haemoglobin release and [Ca2+](i) from Fluo-3 fluorescence. A 48-hr exposure to ribavirin (>= 8 mu g/ml) was followed by a significant increase in [Ca2+](i), a significant decrease in forward scatter and a significant increase in annexin V binding. The annexin V binding after ribavirin treatment was significantly blunted but not abolished in the nominal absence of extracellular Ca2+. In conclusion, ribaverin stimulates eryptosis, an effect at least in part due to entry of extracellular Ca2+.