Acute exacerbation of vasculitis during interferon-alpha therapy for hepatitis C-associated cryoglobulinaemia.

A significant, previously unreported, adverse reaction to interferon-alpha therapy is reported. Immediately after the commencement of low dose therapy a man with hepatitis-C associated cryoglobulinaemia developed a purpuric rash and a severe, reversible impairment of renal function. This observation may elucidate the immunopathogenesis of vasculitis.