The purpose of this study is to determine whether the administration of the study drug is effective in increasing the chance of survival in patients with severe sepsis. Patients entered into this study will be randomly assigned to one of two treatment groups. Patients in each treatment group will be given either the study drug or placebo as a continuous infusion directly into the bloodstream through a catheter placed in one of the patient's veins.

The study drug is an investigational drug that is still in development. It has been studied in approximately 30 healthy subjects, approximately 30 patients with either kidney failure or arthritis, and approximately 600 patients with severe sepsis. Patient participation in this study will last for about one month.

Inclusion Criteria: Patients must

• show evidence of acute infection
• meet specified time windows
• be 18 years of age or older

Exclusion Criteria: Patients must not

• have low white blood cell count
• have undergone certain organ transplants
• be HIV positive
• be pregnant or breast feeding
• have severe underlying medical problems