The purpose of this study is to determine the safety and tolerability of the MDX-1100 regimen in subjects with active Ulcerative colitis(UC) and determine the response rate at day 57 in patients administered MDX-1100.

Inclusion Criteria:

• Subjects with active UC on either 5-ASA,corticosteroids,azathioprine(AZA) and or/6-mercaptopurine(6-MP);

• Mayo score of 6 to 10 points with moderate to severe disease on endoscopy

• Subjects on the following medications;

  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)

Exclusion Criteria:

• Anti-TNF therapy within 8 weeks before study drug administration
• 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
• Evidence of acute or chronic infection
• Clinically significant disease requiring medication