After firm adhesion, neutrophils cross the endothelial barrier by squeezing between adjacent cells at the intercellular junctions. Which molecule, expressed on both leukocytes and endothelial cells, mediates this transmigration step?
- A GlyCam-1
- B E-selectin
- C PECAM-1 (CD31) ✓
- D MAdCAM-1
Correct answer: C. PECAM-1 (CD31)
Explanation
PECAM-1 (CD31) is present at interendothelial junctions and also on the leukocyte surface; homophilic binding between these molecules allows the leukocyte to traverse the junction during diapedesis. Selectins mediate rolling, not transmigration, and GlyCam-1 plus MAdCAM-1 are addressins on high endothelial venules that guide lymphocyte homing rather than neutrophil emigration at sites of acute inflammation.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.