Leukotriene B4 (LTB4) is a potent chemotactic agent for neutrophils. It is derived from which substrate by which enzyme?

• A Arachidonic acid via 5-lipoxygenase (5-LOX) pathway ✓
• B Arachidonic acid via cyclooxygenase (COX) pathway
• C Linoleic acid via cytochrome P450 epoxygenase
• D Membrane phospholipids via phospholipase C

Explanation

LTB4 is synthesized from arachidonic acid through the 5-lipoxygenase pathway, forming 5-HPETE then LTA4, which is converted to LTB4. LTB4 is the most potent neutrophil chemoattractant among arachidonic acid metabolites. The COX pathway produces prostaglandins and thromboxanes, not leukotrienes. CysLTs (LTC4, LTD4, LTE4) from 5-LOX cause bronchoconstriction.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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