Increased Interleukin-1 Production and Monocyte Suppressor Cell Activity Associated with Human Tuberculosis1,2

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Abstract
Interleukin-1 (IL-1) production by blood monocytes and blastogenesis produced by tuberculin purified protein derivative (PPD) in blood T lymphocytes were examined in patients with pulmonary tuberculosis. Monocytes were isolated from blood mononuclear cells by plastic adherence, and IL−1 activity was determined in the mouse thymocyte proliferation assay. Monocytes from patients with tuberculosis produced significantly higher activities of IL−1 than did those from healthy tuberculin reactors when stimulated with lipopolysaccharide (LPS) (patients, 56.1 ± 20.0 U/ml; healthy control subjects, 7.3 ± 1.7 U/ml; p < 0.05) or PPD (patients, 28.1 ± 7.2 U/ml; healthy control subjects, 9.5 ± 2.9 U/ml; p < 0.05). In contrast, PPD-induced blastogenic responses in peripheral blood mononuclear cells (PBMC) from the patients were lower than those from healthy subjects (patients, 4,506 ± 1,145 cpm; healthy control subjects, 14,655 ± 2,240 cpm; p < 0.005), and IL−1 production by monocytes showed a positive correlation with monocyte suppressor activity for PPD-induced blastogenesis. Moreover, exogenous IL−1 was capable of suppressing antigen-induced blastogenesis of PBMC from healthy subjects. These data suggest that monocytes from patients with pulmonary tuberculosis are activated to produce or secrete increased levels of IL−1 and that IL−1 may be a mediator of suppressor cell function.