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BIMM118
Allergy - Leukotrienes
Leukotrienes:
Generated by 5-Lipoxygenase:
Converts AA into 5-HPETE, which in turn is converted into
– LTB4: potent mediator of inflammation
and
– Cysteinyl-LTs (LTC4, LTD4, LTE4 = SRS-A): mediate asthmatic responses
• Physiological actions:
– LTB4:
• Mediated by specific LTB4 receptor
• Adherence, chemotaxis and activation of macrophages
• Stimulates cytokine and chemokine production
• Present in inflammatory exsudates (RA, ulcerative colititis, psoriasis)
– Cys-LTs:
• Mediated by shared receptor for LTC4, LTD4 and LTE4
• Contraction of bronchial muscles (longer lasting than histamine)
• Peripheral vasodilation, coronary vasoconstriction
• Found in sputum of chronic bronchitis, asthmatic lung; lavage of allergic rhinitis