C4A and vasculitis: A prospective cohort study, evaluating the efficacy of new combined therapies with Peg-IFN alpha/RBV/first generation-prothease inhibitors (Boceprevir and Telaprevir) in patients with vasculitis due to HCV-related mixed cryoglobulinemia (MC-HCV) showed that patients, who presented with virological remission, had a reduction of cryoglobulins levels and recovery of C4 fraction of the complement [7].