During acute inflammation, the cellular event that follows neutrophil rolling is selectin-mediated slowing but the firm adhesion step requires:

• A Interaction of E-selectin with sialyl-LewisX on neutrophils
• B Interaction of ICAM-1 on endothelium with CD11b/CD18 (Mac-1) integrins on neutrophils ✓
• C P-selectin binding to PSGL-1 on neutrophils
• D Platelet-activating factor binding to PECAM-1

Explanation

Firm adhesion of neutrophils to the endothelium requires upregulation of integrins on the neutrophil surface (LFA-1/CD11a-CD18 and Mac-1/CD11b-CD18, triggered by chemokines and PAF) binding to their endothelial ligands ICAM-1 and ICAM-2. This high-affinity integrin-ICAM interaction arrests rolling neutrophils and allows transmigration. Selectin-PSGL-1 and selectin-sialyl-LewisX interactions mediate initial tethering and rolling, not firm adhesion. PECAM-1 (CD31) mediates the subsequent transmigration step.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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