CD14 is a pattern recognition receptor for the bacterial cell wall components from Grain-positive and Gram-negative bacteria as well as mycobacteria. Binding of lipopolysaccharide (LPS.) or other cell wall constituents to CD14 initiates signal transduction through the Toll-like receptors resulting in the release of pro-inflammatory cytokines and the initiation of the systemic inflammatory response. In rabbits and non-human primates, CD14 specific antibodies were shown to attenuate responses to LPS or Escherichia coli challenge including pro-inflammatory cytokine release, acute lung injury, hypotension and changes in lung, liver. spleen and adrenal gland morphology. In healthy human Subjects, single doses of a chimeric CD14 antibody (IC14) have been shown to be well tolerated and result in a dose-related degree of saturation of CD14 receptors on monocytes and granulocytes. Pretreatment of healthy subjects with IC14 2 h prior to LPS resulted in an attenuation of the LPS-induced fever. clinical symptoms. and leukocyte activation and degranulation. IC14 inhibited the release of TNF-alpha, IL-6. and IL-10 and delayed the release of sTNFR(1) and IL-1 ra. Further studies are in progress to characterize the safety and clinical pharmacology of IC14 in patients with severe sepsis.