A systemic Vasculitis is found in 5 to 10% of HCV infected patients with mixed cryoglobulinemia (MC). It mainly involves the skin, peripheral nerve and the kidney and may be life threatening. Twenty to 30% of HCV-MC Vasculitis patients are resistant to conventional therapy (i.e. antiviral therapy and/or immunosuppressors) and still have an active disease. Thus, new therapeutic approaches are necessary in such patients. We recently described a regulatory T cell (Treg) deficiency in HCV-related Vasculitis patients. Immunomodulatory effects of interleukin-2 (IL-2) are well established, notably the preferential expansion of Treg able to suppress inflammatory responses mediated by CD4+ and CD8+ T cells.

A systemic Vasculitis is found in 5 to 10% of HCV infected patients with mixed cryoglobulinemia (MC). It mainly involves the skin, peripheral nerve and the kidney and may be life threatening (15% of death). Twenty to 30% of HCV-MC Vasculitis patients are resistant to conventional therapy (i.e. antiviral therapy and/or immunosuppressors) and still have an active disease. An antiviral therapy with Peg-interféron is generally prescribed to control Vasculitis lesions and to slow down the hepatic fibrosis progression. Thus, new therapeutic approaches are necessary in such patients. We recently described a CD4+ CD25+ regulatory T cell (Treg) deficiency in HCV-related Vasculitis patients. Immunomodulatory effects of interleukin-2 (IL-2) are well established, notably the preferential expansion of Treg able to suppress inflammatory responses mediated by CD4+ and CD8+ T cells.

Objective : To evaluate the cellular immune response after IL-2 therapy in HCV-MC Vasculitis patients, resistant to conventional therapy.

Methods : This is an open prospective phase I/II trial. Four cycle of subcutaneous IL-2 therapy (3 millions IU/day from day 1 to 5 every 21 days will be carried out at W1, W3, W6, and W9). The first cure will be carried out with half-dose of IL-2 (1.5 millions IU/day) in the hospital. If the tolerance is satisfactory, the later cures will be done ambulatory. All patients will be followed after IL-2 therapy (S11 to S37).

End points :

1. Clinical tolerance: Absence of Vasculitis flare during and after IL-2 therapy.
2. Immunologic follow-up of Treg and of HCV cellular immune response before, during and after IL-2 therapy.
3. Clinical efficacy: follow-up of clinical manifestations of HCV-MC Vasculitis during and after IL-2 therapy.

Schedule : Duration of patients' inclusion period is estimated 18 months. Duration of therapy and follow-up is estimated 9 months. Analysis of data will last 7 months. Overall duration: 34 months

Inclusion Criteria:

1. HCV+ patients with cryoglobulinemia Vasculitis
2. resistant to conventional therapy (i.e. antiviral therapy and/or immunosuppressors).
3. Vasculitis is defined according to international criteria: chronic HCV infection (HCV RNA+),
4. serum cryoglobulin superior or equal to 0.05g/l in at least two determinations,
5. presence of the triad purpura-arthralgia-asthenia and/or biopsy proven Vasculitis (kidney, nerve or skin).