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