Leukocyte rolling on the vascular endothelium during acute inflammation is primarily mediated by interaction between which receptor-ligand pairs?

• A LFA-1 (integrin) on leukocytes binding ICAM-1 on endothelium
• B Sialyl-Lewis X on leukocytes binding E-selectin/P-selectin on endothelium ✓
• C CXCR2 on leukocytes binding IL-8 secreted by endothelium
• D CD44 on leukocytes binding hyaluronan on endothelium

Explanation

Rolling is the first step in the leukocyte adhesion cascade and is mediated by selectins. Sialyl-Lewis X (sLeX, CD15s) on leukocyte microvilli binds to E-selectin (induced by TNF/IL-1) and P-selectin (released rapidly from Weibel-Palade bodies) on activated endothelial cells, forming transient weak adhesion bonds that cause rolling. Firm adhesion (arrest) involves LFA-1/MAC-1 binding to ICAM-1. CXCR2 mediates chemotaxis (migration), not rolling. CD44-hyaluronan interactions are relevant in lymphocyte homing and inflammation but not the primary rolling mechanism.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.