Which condition increases the risk of reactivation tuberculosis due to impaired macrophage function?

• A. Asbestosis
• B. Langerhans Cell Histiocytosis
• C. Silicosis
• D. Bronchiectasis

Answer: (C)

Impairment of macrophage function that normally contains intracellular pathogens allows latent Mycobacterium tuberculosis to reactivate. Crystalline silica exposure in silicosis injures and kills alveolar macrophages and reduces their microbicidal activity, blunting the intracellular killing of MTB and undermining granuloma containment. This makes reactivation TB more likely in individuals with silica exposure. Other lung conditions listed mainly cause different pathologies (for example, asbestosis is linked to pleural/carcinogenic effects, Langerhans cell histiocytosis involves abnormal dendritic cells, and bronchiectasis reflects chronic airway damage) and do not specifically drive MTB reactivation through macrophage impairment.