Study of Visilizumab Versus Placebo in Subjects With Intravenous Steroid-refractory Ulcerative Colitis Previously Responsive in a Visilizumab Study

Inclusion Criteria: * Males and females, 18 years of age or older. * Only 1 prior treatment course with visilizumab (or placebo in a blinded visilizumab study). * Response (as defined in parent protocol) of intravenous steroid-refractory ulcerative colitis (IVSR-UC) disease to visilizumab or placebo. * Symptomatic worsening (ie, an increase of ≥3 points in MTWSI score) from the subject's best response on the parent study, an MTWSI score of ≥9, sustained for at least 2 assessments performed at least 1 week apart, and a confirmatory MTWSI ≥8 within 1 day prior to randomization. * CD4\^+ T-cell count ≥ 200 cells/mcL at screening for this protocol, or ≥ 80% of the subject's screening baseline count prior to enrollment on the parent study. * Mayo assessment (including flexible sigmoidoscopy) performed by a trained, blinded evaluating physician within 2 weeks prior to randomization. * Adequate contraception from the day of consent through 3 months after the last dose of study drug. * Negative serum pregnancy test. * Negative Clostridium difficile test. * Signed and dated informed consent, and Health Insurance Portability and Accountability Act (HIPAA) if applicable. Exclusion Criteria: * UC requiring immediate surgical, endoscopic, or radiologic interventions. * White blood cell count less than 2.5 x 10\^3/mcL; platelet count less than 150 x 10\^3/mcL; or hemoglobin less than 8 g/dL. * Active, medically significant infections, particularly those of viral etiology, eg, known cytomegalovirus (CMV) colitis. This includes any incidence of opportunistic infections within the past 12 months. * Live vaccination within 6 weeks prior to randomization. * Significant organ dysfunction, including cardiac, renal, liver, CNS, pulmonary, vascular, gastrointestinal, endocrine, or laboratory abnormality, history of myocardial infarction, coronary artery disease, congestive heart failure, or arrhythmias within 6 months prior to consent. * History of lymphoproliferative disorder (LPD) or malignancy other than nonmelanoma skin cancer or carcinoma in situ of the cervix that has been adequately treated within the past five years. * Seropositive for infection with human immunodeficiency virus (HIV-1), hepatitis B virus (HBV) surface antigen, or hepatitis C virus (HCV). * Pregnancy or nursing. * Treatment with any other UC salvage drugs (including but not limited to infliximab or another anti-TNF-a drug, cyclosporine, tacrolimus \[FK506\], adalimumab, thalidomide, or another experimental agent), or therapies (surgery, pheresis, affinity columns) since the first course of treatment with study drug in the parent visilizumab study. * Treatment with any other investigational drug or therapy within 60 days prior to randomization. * Nontherapeutic levels of chronic antiseizure medications in subjects with a history of seizures. * Any condition that, in the investigator's opinion, makes the subject unsuitable for study participation.