Phase I Pilot Study of Total-Body Irradiation, Anti-Thymocyte Globulin and Cyclophosphamide Followed By Syngeneic or Autologous Peripheral Blood Stem Cell Transplantation in Patients With Multiple Sclerosis

PROTOCOL ENTRY CRITERIA: --Disease Characteristics-- Diagnosis of rapidly progressive multiple sclerosis (MS) by Proser criteria and at high risk for a fatal outcome or severe disability with one of the following: * Primary progressive disease * Relapsing/remitting disease with 2 or more attacks in 2 years * Secondary progressive disease Extended disability status scale (EDSS) between 5.0 and 8.0 with deterioration in the EDSS of 1 or more points over the past year More than 60 days since relapse of MS No evidence of myelodysplasia Sibling donor proven to be an identical twin by ABO typing, HLA typing, and VNTR analysis (for syngeneic transplantation) --Prior/Concurrent Therapy-- Radiotherapy: No prior total-lymphoid irradiation Other: No other concurrent investigational agents --Patient Characteristics-- Hepatic: No hepatic impairment that would preclude high-dose immunosuppressive therapy Renal: No renal impairment that would preclude high-dose immunosuppressive therapy Cardiovascular: No cardiac impairment that would preclude high-dose immunosuppressive therapy Pulmonary: No pulmonary impairment that would preclude high-dose immunosuppressive therapy Other: * No neurologic impairment that would preclude high-dose immunosuppressive therapy * No active uncontrolled infection * No active malignancy * No other illness that would severely limit life expectancy * No medical or psychiatric conditions that would preclude study * No history of hypersensitivity to murine proteins or E. coli-derived proteins * No demonstrated lack of compliance with prior medical care * Able to undergo an MRI scan * HIV negative * Not pregnant or nursing