Twenty-four or forty-eight hours (study day 1) prior to the inhalation challenge, subjects will undergo a physical examination of the ears, nose, throat and chest and will have an assessment of vital signs (temperature, pulse, respiratory rate, blood pressure), oxygen saturation, symptom score assessment and undergo spirometry to rule out acute illness prior to challenge. All female volunteers will undergo a urine pregnancy test. A similar examination will take place immediately prior to inhalation challenge with 20,000 EU of CCRE, as well as 30, 60, 120, 180, 240, 300 and 360 minutes and 24 hours after challenge (with the exception of a pregnancy test which will only be administered prior to sputum induction on study day 1). Induced sputum will be 24 to 48 hours prior to challenge, and again six hours after challenge on Study day 2. Sputum will be analyzed for PMN content, CD14 expression on airway macrophages and monocytes, soluble CD14 levels, cytokine levels in sputum and products of inflammatory cells (eosinophil, cationic protein, myeloperoxidase). Blood will be collected for a CBC and differential when the pre- challenge induced sputum is obtained and again 6 hours after challenge and 24 hours after challenge. Blood lymphocytes from a 10 ml aliquot will be assessed for lymphocyte subset and activation markers, as well as proliferative and cytokine responses. Blood will also be collected and will be assessed by whole blood assays for markers of inflammatory and immune activation (CD11b, CD14, CD64, CD16, HLA-DR, CD45, CD3, CD80, CD86, CD83, CD40) and function (phagocytosis and oxidative burst) by three color flow cytometry. Plasma will be separated from 4 ml and frozen at 70° C for future analysis of mediators of interest, such as cytokines, as well as other systemic effects of endotoxin.