Page 88 - Veterinary Immunology, 10th Edition

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FIG. 3.7 Production of leukotrienes and prostaglandins by the
actions of lipoxygenase and cyclooxygenase on arachidonic acid.
Both prostaglandins and leukotrienes may have proinflammatory or
antiinflammatory activity depending on their chemical structure.

Four leukotrienes promote leukocyte recruitment, survival, and
activation. The most important of these, leukotriene B (LTB ) is a
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neutrophil attractant and activator produced by neutrophils,
macrophages, and mast cells. LTB also stimulates eosinophil
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chemotaxis and random motility. Leukotrienes C , D , and E , in
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contrast, increase vascular permeability and cause slow smooth
muscle contraction. All three contain the amino acid cysteine
conjugated to the lipid backbone, so they are called cysteinyl
leukotrienes. They are produced by mast cells, eosinophils, and

basophils. The cytokine interleukin-13 upregulates production of
LTD and its receptor, whereas LTD upregulates IL-13 production.
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This feedback loop is a major contributor to severe inflammation.

There are four groups of proinflammatory prostaglandins: PGE ,
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PGF , the thromboxanes (TxA , PGA ), and the prostacyclins (PGI ).
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Although prostaglandins can be generated by most nucleated cells,

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