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Leukotrienes
🧾 About Leukotrienes
- 🧪 Leukotrienes are lipid mediators derived from arachidonic acid via the lipoxygenase pathway in leukocytes.
- 🌡️ They play a central role in allergic and inflammatory reactions.
- 💧 Increase vascular permeability → oedema and tissue swelling.
- 🧲 Act as chemoattractants, drawing neutrophils & eosinophils to sites of inflammation.
- 🌬️ Leukotriene D4 = “slow-reacting substance of anaphylaxis (SRS-A)” → potent bronchoconstrictor & intestinal smooth muscle contraction.
- 🤧 They also ↑ mucus production → key contributor to bronchial asthma pathophysiology.
📖 Clinical Relevance
- 🔥 In asthma, leukotrienes drive bronchospasm, mucus plugging, and airway oedema.
- 🤒 In allergic rhinitis, they mediate nasal congestion, sneezing, and mucus hypersecretion.
- 💊 Leukotriene receptor antagonists (LTRAs, e.g. montelukast, zafirlukast) block cysteinyl-leukotriene receptors → useful in asthma and allergic rhinitis.
- ⚕️ 5-lipoxygenase inhibitor (zileuton) reduces leukotriene synthesis but is less commonly used (liver monitoring required).
🧩 Pathophysiology in Asthma
🌬️ Triad of leukotriene effects in asthma: 1️⃣ Bronchoconstriction → wheeze, breathlessness 2️⃣ Mucus hypersecretion → sputum plugging 3️⃣ Vascular leak → airway oedema
🧪 Exam / OSCE Tips
- ❓ Leukotriene D4 = SRS-A (slow reacting substance of anaphylaxis).
- ❓ Unlike prostaglandins (can cause bronchodilatation), leukotrienes cause bronchoconstriction.
- 💊 LTRAs are add-on therapy in asthma (esp. exercise-induced or aspirin-sensitive asthma).
- 🧲 Remember: they recruit eosinophils (hallmark of allergic airway inflammation).
📚 References
- Kumar & Clark’s Clinical Medicine, 10th edition.
- BNF – Leukotriene receptor antagonists.
- British Thoracic Society / SIGN Asthma Guidelines.
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
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