A neonate has delayed separation of the umbilical cord, recurrent bacterial infections with absent pus formation, and marked peripheral blood neutrophilia. Neutrophils fail to adhere to endothelium and show no spreading or phagocytosis. The underlying molecular defect is:

• A Defective beta-2 integrins (CD11/CD18) preventing firm adhesion to ICAM-1 ✓
• B Mutation of the common gamma chain of the IL-2 receptor
• C Deficiency of NADPH oxidase in phagolysosomes
• D Absence of the interleukin-8 chemokine receptor CXCR1

Explanation

Leukocyte adhesion deficiency type 1 results from mutations in ITGB2 encoding CD18, the beta chain shared by LFA-1, Mac-1, and p150,95 integrins. Without these integrins, rolling neutrophils cannot adhere firmly to endothelial ICAM-1, so they never exit vessels, producing neutrophilia with no pus and delayed cord separation. NADPH oxidase deficiency (option C) is chronic granulomatous disease, where pus and granulomas are actually prominent because neutrophils reach tissues normally.

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.