Participants will be treated initially with 1 milligram/kilogram body weight of prednisone once a day and 2 to 4 mg/kg cyclophosphamide once a day. If the disease improves significantly, prednisone will be gradually reduced and stopped, and if remission is achieved, cyclophosphamide will be stopped. Methotrexate will then be started at 0.3 mg/kg body weight once a week and then increased to 0.5 mg/kg after 2 to 4 weeks. Methotrexate therapy will continue for at least 2 years. If at the end of 2 years the disease remains in remission, the methotrexate will be gradually reduced and stopped. If, on the other hand, active disease recurs during methotrexate treatment, the therapy will be changed. The new choice of treatment will depend on the severity of recurrence, pre-existing medical conditions, and previous adverse reactions to prednisone, cyclophosphamide and methotrexate.