Patient description: A 57-year-old man was admitted to the clinic because of weight loss and persistent dry cough 4 months ago. Chest computed topography showed bilateral multiple infiltrates in the upper lobes and thickened bronchial walls. There is a documented positive serum MPO-ANCA in his medical record. Transbronchial biopsy revealed necrotic granulomas with multinucleated giant cells and the Wegener's granulomatosis was diagnosed for him. He is treating with corticosteroid and cyclophosphamides since 4 months ago. His Birmingham Vasculitis Activity Score (BVAS) is above 4 since the beginning of his disease. His last physical exam and lab study was performed yesterday and showed the results bellow: A wellbeing, well-nourished man, non-icteric, cooperative and alert Weight: 73 kg Height: 177 BP: 120/80 HR: 90/min RR: 22/min Hgb: 13 g/dl WBC: 8000 /mm3 (Neutrophil: 2700/mm3) Plt: 300000 /ml AST: 40 U/L ALT: 56 U/L Alk P: 147 U/L Bill total: 1.2 mg/dl ESR: 120 mm/hr MPO-ANCA: 153 EU

Clinical trial eligibility criteria: eligible ages (years): 0.0-999.0,  Wegener's Granulomatosis Documentation of WG based on clinical characteristics and histopathologic and/or angiographic evidence of vasculitis. In the absence of histopathologic and/or angiographic evidence of vasculitis, patients who meet one of the following and in whom infectious and autoimmune diseases that may mimic WG have been excluded will also be eligible A positive assay for anti-proteinase 3 or anti-myeloperoxidase autoantibodies (ANCA) and the presence of glomerulonephritis defined by red blood cell casts and proteinuria or renal biopsy showing necrotizing glomerulonephritis in the absence of immune deposits A positive assay for anti-proteinase 3 or anti-myeloperoxidase autoantibodies and at least 2 of the following: the presence of granulomatous inflammation on biopsy; abnormal chest radiograph (defined as the presence of nodules, fixed infiltrates, or cavities); nasal/oral inflammation on clinical examination. Age 18-75 years. Evidence of active disease or if begun on cyclophosphamide (CYC) and glucocorticoids at an outside institution, a history of a active disease at the time of therapy initiation. Willingness to travel to the NIH every 2-4 weeks if they are randomized to receive daclizumab. Willingness of both women and men to use an effective means of birth control while receiving treatment through this study  Evidence of active infection which, in the judgement of the investigator, is of greater danger to the patient than the underlying vasculitis. Patients who are pregnant or who are nursing infants will not be eligible. Women of childbearing potential must have a negative pregnancy test within one week prior to study entry. Serological evidence of infection with human immunodeficiency virus (HIV), hepatitis C, or a positive hepatitis B surface antigen. A serological determination will be performed within two weeks of beginning study participation. Acute or chronic liver disease, past history of alcohol abuse (greater than 14 oz of 100 proof liquor or equivalent per week), ongoing alcohol use of any volume that cannot be discontinued upon entry into the study. History of CYC or methotrexate-induced pneumonitis or other hypersensitivity reactions to these drugs with past treatment. History of transitional cell carcinoma (TCC) of the bladder. History of any malignant neoplasm except in situ anogenital carcinoma, adequately treated basal or squamous cell carcinoma of the skin, or solid tumors (other than TCC of the bladder cancer) treated with curative therapy and disease free for at least 5 years. Inability to comply with study guidelines. Hemocytopenia: platelet count less than 80,000/mm(3), absolute neutrophil count less than 1500/mm(3), hematocrit less than 20% (in the absence of gastrointestinal bleeding or hemolytic anemia). Known allergy to murine proteins