We have continued to use and modify our computerized data bank to analyze an extensive collection of epidemiological, clinical and laboratory information about the systemic vasculitides. We have analyzed data on 60 patients with Takayasu's arteritis seen over a 24 year period and defined the clinical profile and therapeutic outcome of patients with this disease. At least 60% of patients with active disease respond to corticosteroid therapy. In patients refractory to corticosteroid therapy, 40% were able to achieve remission with the addition of a cytotoxic agent. However, 45% of patients achieving remission experienced one or more relapses. Our data indicate that current therapeutic modalities may control disease activity but are potentially toxic and do not prevent disease relapse. Using information in this data bank, we have also retrospectively reviewed the genitourinary morbidity of cyclophosphamide therapy in patients with systemic vasculitis. We had established over the past 25 years that cyclophosphamide therapy is the treatment of choice for the systemic vasculitides, particularly Wegener's granulomatosis. However, in a continued attempt to determine if alternative therapies might provide comparable results without the well- known toxic side effects of cyclophosphamide, we have conducted clinical trials with other immunosuppressive agents. We have continued our study of the efficacy and safety of low dose methotrexate (MTX) in treating Wegener's granulomatosis. At present, follow-up has been adequate to analyze the outcome of 47 patients. The mean duration of follow-up is 19 months. Weekly administration of MTX and corticosteroids resulted in marked improvement in 76% of patients. Sixty four percent of patients were able to achieve remission and have their corticosteroid dose tapered to alternate day therapy or discontinued. A total of 14 patients experienced disease progression while on MTX; three patients experienced MTX toxicity requiring discontinuation of the drug; and there were 3 deaths on therapy. Thus, the total failure rate (disease progression, toxicity, death) was 40%. These results indicate that MTX may be a feasible alternative to daily cyclophosphamide in patients whose illness is not immediately life-threatening or in whom prior cyclophosphamide therapy produced significant toxicity. A phase I/II trial of high dose intravenous immunoglobulin in the treatment of systemic vasculitis has been initiated.