Endotoxin: Complex bacterial toxin; lipopolysaccharide (LPS) component of Gram-negative cell walls is composed of Lipid A + Core Polysaccharide + O Antigen (a.k.a., O polysaccharide side chain) and is released upon lysis of the cell during infection ; Lipid A component is responsible for endotoxin activity effects on the host; O side chain is the antigenic portion of the LPS molecule
Septic shock (sepsis): Associated with overwhelming infection resulting in vascular system failure with sequestration of large volumes of blood in capillaries and veins; Activation of the complement and kinin systems and the release of histamines, prostaglandins, and other mediators may be involved
Endotoxemia: Endotoxin in the blood
Effects of Endotoxin
- Binds to specific receptors on macrophages, B lymphocytes and other cells
- Stimulates release of acute phase immunoreactants and lymphokines (e.g., IFN-g, IL-1, TNF-alpha, IL-6, histamine, prostaglandins)
- Stimulates growth of B cells (mitogenic)
- Fever (Pyrogenicity):
- Any elevation of the body temperature above the normal; functions to speed up immune reactions and to limit/slow bacterial growth and multiplication
- Activation of alternative complement pathway: C3a; C5a
- Circulatory system effects:
- Leukopenia followed by leukocytosis:
- Leukopenia: an abnormal reduction in the number (-penia) of leukocytes inthe blood, (specifically a count of 5000 or less per cubic millimeter)
- Leukocytosis: an abnormal increase in the number (-cytosis) of leukocytes in the blood, as during hemorrhage, infection, inflammation, or fever (specifically a count of 12,000 or more per cubic millimeter), respectively
- Increased vascular permeability (vasodilation)
- Decreased peripheral circulation
- Decreased perfusion (blood flow) of blood to major organs
- Capillary leakage; microhemorrhage; formation of petechiae (round, purple lesions caused by intradermal or submucosal microvascular hemorrhaging)
- Hypotension (low blood pressure)
- Effects on blood coagulation:
- (DIC) Disseminated intravascular coagulation:
- Disorder characterized by a reduction in the elements involved in blood coagulation due to their utilization in widespread blood clotting within the vessels; Late stages marked by profuse hemorrhaging
- Activation of clotting pathway
- Thrombosis: Formation of blood clot (thrombus) in heart or blood vessel
- Thrombocytopenia: Abnormally low numbers of blood platelets
- Effects on metabolic and liver functions
- Decreased iron availability
- Hypoglycemia: Abnormally low glucose levels
- Cellular death (cytotoxicity)
- Organ necrosis:
- Sum of morphological changes indicative of cell death and caused by the progressive degradative action of enzymes
- Shock:
- Characterized by failure of the circulatory system to maintain adequate blood flow to the vital organs
- Symptoms include: Hypotension; Weak pulse; Rapid and shallow breathing; Low body temperature; CNS (central nervous system) effects (e.g., nausea)
- Death
Designed & Maintained by David M. Rollins
Copyright © 2000, D.M. Rollins and S.W. Joseph
Revised: September 2003
URL: http://life.umd.edu
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