ISIS 2302 is an antisense oligonucleotide drug that reduces the production of a specific protein called intercellular adhesion molecule (ICAM-1), a substance that plays a significant role in the increase of inflammation. People with Crohn’s disease have been shown to over-produce ICAM-1 in their gut tissues. Alicaforsen works by blocking ICAM-1 messenger RNA, the “instruction” molecule that is required for the production of ICAM-1 protein. This trial will examine effects of alicaforsen delivered by 2-hour intravenous infusion over a four-week period, compared to a placebo. Patients may remain on stable background 5-ASA, antibiotic, or immunosuppressive drugs, and prednisone (or equivalent) at </= 30 mg per day.