Aktywność biologiczna lipopolisacharydu bakteryjnego
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The purpose of this paper is to briefly review the structure and biological activity of bacterial endotoxin. Endotoxin or lipopolisaccharide (LPS) is the major component of the ou ter membranes of the cell walls of Gramm-negative bacteria. LPS consists of two parts: the hydrophobic lipid A and hydrophylic polysaccharide with contrasting chemical and physical properties. The toxic activity is principally due to its lipid A moiety. LPS is capable of inducing stimulation of immunological system acting on monocytes, macrophages, granulocytes, platelets and endothelial cells leading to the release of inflammatory mediators: eicosanoids, cytokines, chemokines, adhesion molecules, reactive free radicals, platelet activating factor (PAF) and NO'. In the circulation LPS may bind to plasme components such as high-density lipoproteins (HDL) or LPS binding protein (LBP). This complex interacts with a high affinity receptor CD14 expressed on leukocytes, monocytes and macrophages resulting in activation of these cells and inducing pathophysiological effects such as inflammation, septic shock and death. The consequences for the host of all these events are dependent on the extent of LPS exposure and the status of the host defense mechanisms.