Hu Mik-Beta-1 to Treat HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis

* INCLUSION CRITERIA: Patients must be at least 18 years old. Patients must have a diagnosis of HAM/TSP as defined by the WHO criteria, including a positive HTLV-I EIA and confirmatory pattern on Western Blot analysis. Other causes of chronic progressive myelopathy are excluded by tests for serum B12 level, Lyme disease serologies, RPR, anti-nuclear antibody (ANA), extractable nuclear antigen (ENA) screen and magnetic resonance images of brain and spinal cord. At least 7% of each patient's peripheral blood mononuclear cell population must react with anti-CD122 immunofluorescent cell staining. Spontaneous lymphoproliferation and HTLV-I specific cytotoxic T lymphocyte responses must be demonstrated by the patient's peripheral blood mononuclear cells in ex vivo culture. Patients must be willing to comply with all aspects of the dosing and evaluation procedure including taking the required medications and should be willing to return for the follow-up visits. Patients must be able to provide written, informed consent prior to any testing under this protocol, including screening and baseline investigations that are not considered part of routine patient care. EXCLUSION CRITERIA: EDSS greater than or equal to 7 (unable to walk beyond approximately 5 meters even with aid, essentially restructed to wheelchair). Any contraindication to monoclonal antibody therapy, including serious adverse events related to prior monoclonal antibody therapy. Patients who have received prior antibody therapy will have pertinent medical records reviewed by the study investigator. Subjects with prior monoclonal antibody use (especially murine MiK- Beta 1) and allergy/sensitivity to murine MiK- Beta 1 are excluded. Any vaccination within 30 days prior to study entry. Any chronic bacterial, mycobacterial, other viral (e.g. herpes virus), fungal, parasitic or protozoal infection. History of malignancy (active or within the previous 5 years). History or signs of immunodeficiency Subjects with pre-existing cardiac disease, abnormal baseline echocardiogram or significantly abnormal ECG will undergo evaluation by a cardiologist, and will be excluded if, in the opinion of the cardiologist, participation in the study would compromise the safety of the patient. Subjects with history or laboratory evidence of thrombosis or hypercoagulable state. Concurrent medical condition that in the opinion of the investigator would compromise the safety of the patient. HAM/TSP patients with co-existing HTLV-I associated medical conditions, such as uveitis, alveolitis or keratoconjunctivitis sicca are not excluded unless, in the opinion of the investigator, participation in the protocol would compromise the safety of the patient. However, patients with clinically significant co-morbid neuromuscular conditions such as inflammatory myopathies and neuropathies are excluded. Patients with cognitive impairment who are unable to provide written, informed consent. The patient has received an investigational drug for this condition within 6 months prior to entering the study. Contraindication to prophylactic anticoagulation with low molecular weight heparin such as history of hypersensitivity to enoxaparin, haparin, pork products, or any component of the formulation (including benzyl alcohol in multiple-dose vials); thrombocytopenia associated with a positive in vitro test for antiplatelet antibodies in the presence of enoxaparin The patient requires concurrent therapy with other immuno-modulating agents including interferons, corticosteroids and daclizumab. Serious illness requiring systemic treatment and /or hospitalization until the subject either completes therapy or is clinically stable (in the opinion of the investigator) on therapy for at least 14 days prior to the first dose. Abnormal screening/baseline tests exceeding any of the limits defined below: * Total white blood cell count less than 3000/mm(3) * Platelet count less than 85,000/mm(3) * INR greater than or equal to 1.5 * Serum creatinine level greater than 1.5 mg/dL * Serum alanine transaminase or aspartate transaminase levels which are greater than two times the upper limit of normal values. * Serum creatine kinase levels that are greater than two times the upper limit of normal values. * Serological evidence of HIV, HTLV-II, hepatitis B or C. * Positive pregnancy test * Positive PPD * Positive RPR * Positive rheumatoid factor * Abnormal TSH * Abnormal B12 or folate levels * Positive Lyme ELISA or Western Blot * Positive lupus anticoagulant Results of any of the following tests suggestive of an alternative diagnosis that can fully account for the clinical presentation: * Positive RPR * Positive rheumatoid factor * Abnormal TSH * Abnormal B12 or folate levels * Positive Lyme ELISA or Western Blot * Positive lupus screen (ANA/ENA) * Pregnant or lactating patients * Women who are not using an acceptable method of contraception. Acceptability of various methods of contraception will be determined by the investigator. Postmenopausal or surgically sterile women must have documentation of postmenopausal status or surgical sterility available prior to enrollment. * Men who are not practicing adequate contraception. Acceptability of various methods of contraception will be determined by the investigator. Surgically sterile men must have documentation of surgical sterility available prior to enrollment. * Active drug or alcohol use or dependence that in the opinion of the investigator would interfere with adherence to study requirements. * Unwillingness or inability to comply with the requirements of this protocol including the presence of any condition (physical, mental or social) that is likely to affect the patient returning for follow-up visits on schedule. * Subjects who withdraw from this study may not re-enter. Patients who have received prior investigational therapy for HAM/TSP including daclizumab and interferon must be off the investigational therapy for 6 months prior to enrollment.