The influence of carbon particles on the concentration of acid phosphatase and lysozyme enzymes within alveolar macrophages during the killing and degradation of Mycobacterium bovis

Setting: Diagnostic bronchoscopy performed on untreated African patients with tuberculosis revealed alveolar macrophages filled with carbon particles. It was postulated that this was the result of excessive inhalation of smoke from domestic fires and the consequent phagocytosis by alveolar macrophages. Objective: To determine whether carbon particles influence acid phosphatase and lysozyme enzyme concentrations during the killing and degradation of Mycobacterium bovis by alveolar macrophages. Design: Alveolar macrophages were recovered by bronchoalveolar lavage from adult rabbits and cultured. Experimental cultures were exposed to M. bovis and carbon particles, and controls only to M. bovis. Cultures were grown for 42 h for killing and degradation of organisms. Cells were microscopically enumerated for carbon particle content and enzyme stain intensity. The level of significance was determined by means of a statistical test for sample proportions and by using Student's t-test. Results: The majority of alveolar macrophages in the experiments contained large amounts of carbon particles. The average percentage of alveolar macrophages that stained positive for acid phosphatase and lysozyme enzymes is significantly lower in the experiments than in the controls (P < 0.01 and P < 0.001 respectively). Conclusion: It is concluded that large amounts of carbon particles significantly decrease these enzyme concentrations intracellularly.