Nature and extent of the burden and risks associated with participation, benefit and group relatedness: A medical interview and physical examination is part of this study. Approximately 350 ml blood will be withdrawn and urine will be collected. There will be mild discomfort associated with participation in this study, as LPS induces flu-like symptoms for approximately 4 hrs. GTS-21 was found to be well tolerated at a dose of 150 mg three times daily (450 mg/day).