Monocyte/macrophage functions & humoral response in blood & bronchoalveolar lavage fluid of pulmonary tuberculosis patients.

Subsegmental bronchoalveolar lavage (BAL) was performed in 33 patients with active pulmonary tuberculosis and five control subjects. Phagocytosis by monocytes and alveolar macrophages was studied, and in addition serum and BAL immunoglobulin and complement levels were also determined. The phagocytic activity of blood monocytes was depressed in pulmonary tuberculosis patients as compared to controls, 37.8 +/- 2.3 per cent; 50.7 +/- 4.2 per cent and 32.9 +/- 3.6 per cent for sheep RBC's, latex and Staphylococcus aureus respectively compared to 66.7 +/- 6, 54.8 +/- 2.2 and 68.3 +/- 3.5 per cent respectively in controls; the differences being significant for sheep RBC's (P less than 0.05) and Staph. aureus (P less than 0.001). However, phagocytosis was not impaired in BAL macrophages (P greater than 0.05). In patients no significant alteration in serum immunoglobulin and complement levels was observed except that levels of C4 component of complement were increased in patients with far advanced lesions (98.5 +/- 33.7 mg/dl compared to 78.7 +/- 7.9 mg/dl; P less than 0.05). While IgM and C4 component of complement could not be detected in BAL fluid the levels of IgA were significantly increased in pulmonary tuberculosis patients (65.5 +/- 50.5 mg/dl compared to 39.9 +/- 13.3 mg/dl in control; P less than 0.05). Since IgA secreted in the BAL fluid is mostly synthesised locally, increased levels of this immunoglobulin could be of value in determining activity of the disease.