Immune thrombocytopenia and alpha-interferon therapy.

Thrombocytopenia is often found in patients with liver diseases, especially due to congestive splenomegaly caused by portal hypertension. Immune thrombocytopenia has been described rarely, and it seems to be especially associated with hepatitis C virus, which has been described as having a particular interaction with the immune system contributing to the induction of autoimmunity. Interferons, on the other hand, because of their immunomodulatory properties, are able to induce or exacerbate autoimmune diseases. Mild thrombocytopenia is a common adverse effect of interferon therapy. Severe life-threatening thrombocytopenia is extremely rare. We report two cases of severe immune thrombocytopenia in patients with chronic hepatitis C, probably induced by alpha-interferon. Bone marrow aspirate and elevated platelet-associated IgG antibodies, determined by indirect immunofluorescence, were suggestive of immune thrombocytopenia. None of the patients had any clinical sign of autoimmune syndrome, including arthritis, serositis, Sicca syndrome, vasculitis, thyroid abnormalities and others. Cryoglobulins and rheumatoid factor were tested and were undetectable. The patients' histories of exposure to alpha-interferon and the exclusion of other causes are most consistent with drug-induced immune thrombocytopenia. After alpha-interferon withdrawal, thrombocytopenia was treated successfully with prednisolone and immunoglobulins. Response to treatment was consistent with the diagnosis of alpha-interferon-induced immune thrombocytopenia and peripheral consumption of platelets.