Leukotriene B4 (LTB4) is a potent chemoattractant for neutrophils. It is generated from arachidonic acid by which enzymatic pathway?

• A 5-Lipoxygenase pathway ✓
• B Cyclooxygenase-1 pathway
• C Cyclooxygenase-2 pathway
• D Cytochrome P450 epoxygenase pathway

Explanation

Arachidonic acid is metabolized by 5-lipoxygenase (5-LOX) to 5-HPETE and then to LTA4, which is converted to LTB4 (potent neutrophil chemotactic) or to cysteinyl leukotrienes (LTC4, LTD4, LTE4) which cause bronchoconstriction. The cyclooxygenase (COX-1 and COX-2) pathways produce prostaglandins, thromboxane, and prostacyclin, not leukotrienes. Cytochrome P450 epoxygenase produces epoxyeicosatrienoic acids.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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