Following the four infusions, there will be blood tests to monitor the safety of the medication and the status of the disease, to be done at home every week for 4 weeks. Results will be sent to the researchers by fax. Patients will be asked to return to the clinic 1 month after the fourth infusion and every 1 to 3 months afterward. If there are no side effects or a relapse of the disease, the methotrexate or azathioprine will be continued for 2 years past remission. If by then the disease then remains in remission, the dose of either medication will be gradually decreased and eventually stopped. The usual schedule is to reduce methotrexate by 2.5 mg per month and to reduce azathioprine by 25 mg per month. If at that point there are no signs of active disease, the patients' illness will be considered to be in continued remission and no further treatment will be necessary. If relapse does occur, treatment would be different than previously. In most cases, treatment would involve prednisone and cyclophosphamide or methotrexate If the ANCA finding is negative after rituximab treatment and again becomes positive, and there is evidence of a return of B lymphocytes, patients may receive a second course of four rituximab infusions.