After firm adhesion of neutrophils to endothelium, leukocytes traverse the vessel wall between adjacent endothelial cells. Which molecule, expressed at endothelial cell junctions, mediates this transmigration step?
- A PECAM-1 (CD31) ✓
- B E-selectin
- C VCAM-1
- D GlyCAM-1
Correct answer: A. PECAM-1 (CD31)
Explanation
PECAM-1 (CD31) is a member of the immunoglobulin superfamily located at interendothelial junctions; it engages its counterpart on the leukocyte surface and guides the cell through the junction during diapedesis. E-selectin and VCAM-1 act earlier, in rolling and firm adhesion respectively, and GlyCAM-1 is a peripheral lymph node addressin involved in lymphocyte homing, not neutrophil transmigration.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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