Patient description: A 17 year old boy complains of vomiting, non-bloody diarrhea, abdominal pain, fever, chills and loss of appetite for the past 3 days. He ate a salad at a restaurant prior to his diarrhea onset. Physical exam was remarkable for pallor, jaundice, and diffuse abdominal tenderness. Lab results were as follows: Hemoglobin: 9.7 g/dL Platelet: 110,000 /cu.mm Creatinine: 3.6 mg/dL blood urea nitrogen (BUN): 73 mg/dL direct bilirubin: 2.4 mg/dL lactate dehydrogenase (LDH): 881 IU/L (normal: 110-265 IU/L) Peripheral blood smear showed a moderate number of schistocytes and helmet cells. Shiga-like toxin-producing E. coli (STEC) stx1/stx2 were found in stools. He has no other underlying disease and he is not on any medications.

Clinical trial eligibility criteria: eligible ages (years): 18.0-999.0,  Crohn's Disease All subjects must have a verifiable diagnosis of active Crohn's disease of at least 4 months' duration. The diagnosis must be supported by characteristic 1) endoscopic or radiographic findings and 2) histopathologic changes on endoscopic biopsy or resected tissue. All subjects must be over age 18. The Crohn's disease is mildly to moderately active based on a Crohn's Disease Activity Index score between 225 and 450 (with either a diarrhea rating or abdominal pain rating of greater than or equal to 25). If currently receiving any medications for Crohn's disease, subjects may only be on a stable regimen of one or a combination of the following drug doses and durations: antibiotic therapy for greater than or equal to 2 weeks; Corticosteroids (less than or equal to 25 mg Prednisone/d, or Prednisone equivalent) for greater than or equal to 4 weeks; 5-ASA/Sulfasalazine for greater than or equal to 4 weeks; azathioprine/6-MP for greater than or equal to 8 weeks (Note: patients receiving Azathioprine or 6-MP must have been receiving these medications for greater than or equal to 12 weeks before randomization.); Probiotics for greater than or equal to 4 weeks. Use of barrier or hormonal methods of birth control for male and famale subjects who are not surgically sterile or postmenopausal. Negative serum beta-hCG for women of child-bearing potential (women who are not surgically sterile or postmenopausal) to early pregnancy. Negative results on stool examination for culture of enteric pathogens (Salmonella, Shigella, Yersinia, Campylobacter, Vibrio, E. coli O157/H7), Clostridia difficile toxin assay, enteric parasites and their ova (including Giardia and Cryptosporidia)  If any one of the above requirements is not met. Use of any the following medications within the specified time period prior to the first dose of study drug or at any time during the study: Corticosteroid enema or 5-ASA enema or suppositories (7 days); Thalidomide (2 weeks); Corticosteroids (greater than 25 mg Prednisone/d or Prednisone equivalent) (4 weeks); Methotrexate, Cyclosporin, Tacrolimus (FK506, Prograf), Thalidomide, or Mycophenolate mofetil (CellCept) (4 weeks), or any biological therapy (cytokine, anti-cytokine, or integrin-based therapy); Monoclonal antibodies to TNF (4 months); any experimental agent (1 month); use of greater than 500 mg/d aspirin or any dose of other NSAID (24 hours). Multiple bowel resections (greater than or equal to 200 cm) AND enteral or parenteral therapy to maintain weight. Use of any other investigational agent within 30 days beginning the treatment phase of this study. Any of the following abnormalities on an electrocardiogram: QT(c) greater than 0.48 sec, Mobitz type II second or third degree atrioventricular block, left bundle branch block or right bundle branch block with any fascicular block, changes consistent with acute ischemia. A diagnosis of ulcerative colitis or indeterminate colitis; Cushing's syndrome; Coexisting Th2-type inflammatory diseases: a.) scleroderma b.) persistent asthma defined as the presence of one of the features listed below: Clinical features before treatment: daily symptoms, exacerbations that affect activity and sleep, nighttime asthma symptoms two to four times a week, peak expiratory flow (PEF) or forced expiratory volume (FEV1) greater than 60 percent to less than 80 percent of predicted, variability greater than 30 percent; Daily medication required to maintain control: Daily controller medication (especially for nighttime symptoms): inhaled corticosteroids and long acting bronchodilators persistent asthma defined as the presence of one of the features listed below: Clinical features before treatment: continuous symptoms, frequent exacerbations, frequent nighttime asthma symptoms more than 4 times a week, daily physical activities limited by asthma symptoms, PEF or FEV1 less than 60 percent predicted, variability greater than 30 percent; Daily medication required to maintain control: Multiple daily controller medications (long-term); high-dose inhaled corticosteroids or bronchodilators oral corticosteroids Current active bowel obstruction, intestinal perforation, significant GI hemorrhage, or known presence of high grade structure HIV positivity or signs and symptoms consistent with HIV infection Acute systemic or intestinal infection requiring antibiotics Active hepatitis B or C Decompensated liver disease (Childs-Pugh class B or C) Hematocrit less than 30 percent; Platelet count less than 100,000 or greater than 700,000; PT INR greater than 1.3 or PTT prolonged by greater than 3 seconds; serum creatinine or BUN greater than 1.5 times the upper limit of normal (ULN); ALT(SGPT) or AST(SGOT) greater than 2 times the ULN; total bilirubin greater than 1.25 times the ULN; alkaline phosphatase greater than 1.5 times the ULN. Pregnant or nursing women History of cancer (other than resected cutaneous basal or squamous cell carcinoma; and in situ cervical cancer) with less than 5 years documentation of a disease-free state History of myocardial infarction within the last 12 months Patients expected to require surgery for their Crohn's disease within 12 weeks of study entry. Any condition that, in the investigator's opinion, places the patient at undue risk by participating in the study. History of anaphylactic reaction or hypersensitivity to G-CSF (Filgrastim) or proteins derived from E. coli Presence of splenomegaly defined as a palpable spleen on physical exam