Intravenous Immunoglobulin After Relapse in Vasculitis

Inclusion Criteria: * Wegener's granulomatosis, Microscopic polyangiitis and Churg-Strauss syndrome (satisfying ACR or chapel Hill classification) relapsing either under corticosteroid and immunosuppressant therapies or after one year post treatment * Age \> 18 years old * Written informed consent Exclusion Criteria: * Systemic vasculitides not previously treated with corticosteroid and immunosuppressant(s) * Systemic vasculitides treated with corticosteroids and immunosuppressant therapies, but with treatment cessation more than 12 months ago * Polyarteritis nodosa * Absence of poor prognosis criteria (according to FFS) * Nephritis ± renal impairment * Cancer or malignancy * Psychiatric disease, lack of compliance * Age under 18 years old * Lack of written informed consent * Other vasculitides (post viral infection and skin localisation)