Increase in tumor necrosis factor alpha- and interleukin-6-secreting cells in peripheral blood mononuclear cells from subjects infected with Mycobacterium tuberculosis

Abstract

We detected and quantified tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) from monocytes/macrophages (M∅) in the peripheral blood of subjects from three different population groups, i.e., tuberculin-negative healthy subjects, tuberculin-positive healthy subjects, and patients with active pulmonary tuberculosis. TNF-α or IL-6 activity in the culture supernatant of these cells was determined by the cytotoxicity of murine L-929 cells or by enzyme-linked immunosorbent assay, respectively. Detection and enumeration of cells secreting either TNF-α or IL-6 were performed by an adaptation of the enzyme-linked immunospot assay. Monocytes/M∅ from tuberculin-positive healthy subjects or patients with tuberculosis showed higher TNF-α- and IL-6-producing activities than those from tuberculin-negative healthy subjects. The number of TNF-α- and IL-6-secreting cells in either lipopolysaccharide- or muramyl dipeptide-stimulated mononuclear cells from tuberculin-positive healthy subjects and patients was significantly higher than that in cells from the tuberculin-negative healthy subjects.