Endotoxin

Endotoxin is the lipopolysaccharide (LPS) of the outer membrane of many Gram-negative bacteria. Its lipid A portion can trigger strong inflammatory responses when released or exposed to the host.

Lipopolysaccharide: A molecule composed of lipid and polysaccharide that forms a major part of the outer membrane of Gram-negative bacteria. Endotoxin is the biological activity associated with this outer-membrane molecule.
Limulus amebocyte lysate test: A laboratory assay that detects endotoxin through a clotting reaction in horseshoe crab blood cells. It is a widely used method for measuring endotoxin contamination.
Exotoxin: A protein toxin secreted by bacteria or released from bacterial cells. Unlike endotoxin, it is a protein rather than a membrane component.
Endotoxic shock: A form of circulatory shock associated with severe systemic exposure to bacterial endotoxin. It is a severe possible consequence of endotoxin-driven inflammation.
Lipid A: The phosphorylated lipid portion of lipopolysaccharide that anchors it in the bacterial outer membrane. This region is chiefly responsible for LPS-triggered inflammation.
Bacterial endotoxin test: A compendial test used to detect or quantify bacterial endotoxins in products such as injectable drugs. The LAL assay is one established method within this broader testing category.
Gram-negative bacteria: Bacteria whose cell envelope has a thin peptidoglycan layer and an outer membrane. Their outer membrane is the principal bacterial source of endotoxin.
Disseminated intravascular coagulation: A syndrome in which widespread coagulation activation causes both clotting and bleeding. Severe endotoxin-associated inflammation can activate coagulation pathways.
Toll-like receptor 4: An innate immune receptor that recognizes bacterial lipopolysaccharide with help from accessory proteins. Its activation initiates many host responses to endotoxin.
Recombinant factor C assay: An endotoxin assay using a recombinant version of the horseshoe crab protein that initiates the LAL clotting cascade. It offers an animal-free alternative for detecting endotoxin.

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