We describe a patient who developed progressive inflammatory polyarthr
itis after treatment with interferon-alpha (IFN-alpha) for chronic hep
atitis C infection. Rechallenge with the drug caused worsening of the
arthritis, but withdrawal did not result in remission. Preexisting aut
oantibodies and HLA-DR4 were detected in his serum and are thought to
be relevant in the etiology of IFN-alpha associated autoimmune disease
.