Inclusion Criteria:

• 18 years of age or older
• Active UC (as defined in Appendix 3) on 5-ASA therapy and also treated with 6-MP and/or corticosteroids or who have previously been treated with AZA, 6-MP or corticosteroids and could not tolerate them
• Mayo score of 6 to 10 points with moderate to severe disease on endoscopy (Mayo score of at least 2) performed ≤ 14 days of study drug administration

• Subjects on the following medications may be enrolled into the study if the medications were according to the following schedules prior to study drug administration and if no changes are anticipated during the study;

  1. prednisolone ≤ 20 mg daily (or equivalent) (dose must be stable for at least 2 weeks prior to study drug administration)
  2. 5-ASA (dose must be stable for at least 4 weeks prior to study drug administration)
  3. AZA or 6-MP (dose must be stable for at least 3 months prior to study drug administration)
  4. Rectal steroids or 5-ASA (must have been stable for at least 4 weeks prior to study drug)
• Subjects using rectal medications must have visible disease on sigmoidoscopy at ≥ 20 cm
• Screening laboratory values must meet certain criteria:
• Women must be postmenopausal (> 12 months without menses) or surgically sterile (e.g., by hysterectomy and/or bilateral oophorectomy) or must be using effective contraception (e.g., oral contraceptives, intrauterine device (IUD), double barrier method of condom and spermicidal) for at least 4 weeks prior to study drug administration and agree to continue contraception for the duration of their participation in the study; and
• Sexually active male subjects must use a barrier method of contraception during the duration of the study.

Exclusion Criteria:

• Anti-TNF therapy within 8 weeks before study drug administration
• Any experimental therapy more therapy ≤ 4 weeks before study drug administration
• Prior treatment with any monoclonal antibody or immunoglobulin-based fusion proteins ≤ 8 weeks prior to study treatment
• Presence of Cushing's syndrome
• Toxic megacolon or fulminant disease likely to require colectomy
• Contraindication to colonoscopy or sigmoidoscopy
• Primary or secondary immunodeficiency
• Autoimmune disease besides UC, with the exceptions of Sjogren's syndrome or hypothyroidism
• History of malignancy, excluding adequately treated and cured basal or squamous cell of the skin, or cervical carcinoma in situ
• Major psychiatric disease (subjects with stable depression receiving appropriate management will be permitted in the study);
• Evidence of acute or chronic infection as evidenced by:
• stool culture positive for pathogens and/or Clostridium difficile toxin
• findings on Screening chest radiography such as pulmonary infiltrate(s) or adenopathy
• current treatment for tuberculosis infection, clinical or radiological evidence of active TB, or for subjects in North America, a positive PPD without prior prophylaxis
• Herpes zoster ≤ 3 months prior to study drug administration
• active infectious disease requiring i.v. antibiotics within 4 weeks prior to study treatment or oral antibiotics at the time of enrollment
• HIV or AIDS
• positive tests for HBV, or HCV indicating active or chronic infection
• Clinically significant cardiac disease requiring medication, unstable angina, myocardial within 6 months, or congestive heart failure
• Arrhythmia requiring active therapy, with the exception of clinically insignificant or minor conduction abnormalities
• History of cerebrovascular disease requiring medication/treatment
• Anticoagulation therapy or a known bleeding disorder
• Seizure disorder requiring active therapy
• Known drug or alcohol abuse
• Pregnant or nursing
• Any underlying medical condition that in the Principal Investigator's opinion will make the of study drug hazardous to the subject or would obscure the interpretation of treatment efficacy or safety; or
• Inability or unwillingness to return for Follow-up visits and comply with study protocol.