Impairments of Antigen-Presenting Cells in Pulmonary Tuberculosis

Abstract

The phenotype and functional properties of antigen-presenting cells (APC), that is, circulating monocytes and generatedin vitromacrophages and dendritic cells, were investigated in the patients with pulmonary tuberculosis (TB) differing in lymphocyte reactivity toM. tuberculosisantigens (PPD-reactive versus PPD-anergic patients). We revealed the distinct impairments in patient APC functions. For example, the monocyte dysfunctions were displayed by low CD86 and HLA-DR expression, 2-fold increase in CD14+CD16+expression, the high numbers of IL-10-producing cells, and enhanced IL-10 and IL-6 production upon LPS-stimulation. The macrophages which werein vitrogenerated from peripheral blood monocytes under GM-CSF were characterized by Th1/Th2-balance shifting (downproduction of IFN-γcoupled with upproduction of IL-10) and by reducing of allostimulatory activity in mixed lymphocyte culture. The dendritic cells (generatedin vitrofrom peripheral blood monocytes upon GM-CSF + IFN-α) were characterized by impaired maturation/activation, a lower level of IFN-γproduction in conjunction with an enhanced capacity to produce IL-10 and IL-6, and a profound reduction of allostimulatory activity. The APC dysfunctions were found to be most prominent in PPD-anergic patients. The possible role of APC impairments in reducing the antigen-specific T-cell response toM. tuberculosiswas discussed.