B

Reduced neutrophil chemotaxis is a well-documented host-defense defect in localized juvenile (aggressive) periodontitis and is closely linked to the excessive periodontal bone loss seen in these patients [Clark, 1977, PMID 591063; Van Dyke, 1980, PMID 7358424]. Impaired chemotactic migration limits neutrophils’ ability to reach and contain subgingival pathogens, allowing unchecked inflammation and osteoclastic bone destruction.