Which arachidonic acid metabolite is the primary chemotactic agent for neutrophils in acute inflammation, generated via the 5-lipoxygenase pathway?
- A Leukotriene C4 (LTC4)
- B Leukotriene B4 (LTB4) ✓
- C Thromboxane A2 (TXA2)
- D Prostacyclin (PGI2)
Correct answer: B. Leukotriene B4 (LTB4)
Explanation
LTB4 is produced by the 5-LOX pathway (FLAP + 5-LOX convert AA to 5-HPETE then LTA4, which is hydrolyzed to LTB4) and acts as a potent chemoattractant for neutrophils via BLT1 receptors, also activating neutrophil adhesion and degranulation. Cysteinyl leukotrienes (LTC4, LTD4, LTE4) cause bronchoconstriction and increased vascular permeability. TXA2 promotes platelet aggregation and vasoconstriction. PGI2 (prostacyclin) inhibits platelet aggregation and causes vasodilation — counteracting TXA2.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.