Phagocytosis and the antigen-processing abilities of macrophages derived from monocytes in spinal tuberculosis patients

This study examined the hypothesis that there is an impairment of macrophageal function in spinal TB. We examined macrophageal functions in spinal TB patients. Monocytes were isolated from peripheral blood mononuclear cells (PBMCs) of five spinal TB patients and five healthy persons as control. The isolated monocytes were cultured with stimulation of macrophage colony-stimulating factor (M-CSF) for seven days for maturation. The phagocytic ability of the macrophages derived from monocytes was measured. Also, nitric oxide (NO), myeloperoxidase (MPO), beta-glucuronide, and acid phosphatase activity was investigated. We found that the monocytes collected from patient PBMCs were significantly fewer than those of the control group (2992.10³ vs. 6474.10³ (cells/mL)). There were also fewer macrophages that had adhered to sheep red blood cells (SRBC) (598.10³ vs. 264.10³ (cells/mL)). However, NO production (2346 vs. 325.17 (µmol/gram of protein)), and the MPO (570.7 vs. 17.4 (unit/mg), beta-glucuronide (0.149 vs. 0.123 (μmol/hour/100 mg of protein)), and acid phosphatase activities (1776.9 vs. 287.9 (μmol/hour/100 mg of protein)) of the macrophages in the spinal TB group were markedly higher than in the healthy group. Despite the low adhesion to foreign bodies, the intracellular processing of TB macrophages, including oxidative activity and lysosome function, was significantly high. These results suggested the impairment of macrophageal function in spinal TB. Possibly, there is a dominance of innate non-specific immunity in spinal TB infection.