Dendritic cells and the regulation of a granulomatous immune response in the lung.
To investigate the contribution of dendritic cells (DC) in a pulmonary granulomatous immune response, C57BL/l6 mice, nonimmunized or immunized with purified protein derivative (PPD) of Mycobacterium bovis, were intravenously injected with PPD-coated Sepharose-4B beads. One and three days later lungs were harvested, granuloma size was measured, and immunolabeled cells in granulomas were counted. On Day 1, granulomas in immunized mice were 3-fold larger and contained more major histocompatibility complex class II+, CD11c+ DCs than nonimmunized mice. By Day 3, these differences had diminished. In all granulomas MHC class II+, CD11c+ DCs were in contact with the beads. By in situ hybridization these DCs expressed interleukin (IL)-12 p40 mRNA. MOMA2+ macrophages were present throughout the granulomas, whereas CD4+ and CD8alpha+ T cells were localized at the granuloma periphery. DCs isolated from granulomatous lungs at Day 1, and from thoracic lymph nodes (LNs) at Days 1 and 3, stimulated PPD-specific T cell proliferation without exogenously added antigen, indicating that they had acquired bead-bound antigen. By Day 3, however, granuloma DCs presented little antigen, suggesting that newly immigrated DC lacked access to antigen or that antigen uptake/processing was inhibited. RNase protection assays of whole-lung mRNA showed increased interferon-gamma, IL-1beta, IL-1 receptor antagonist, IL-6, and macrophage inhibitory factor, but no IL-10 mRNA on Days 1 and 3. These observations support the premise that DCs are key in initiating granulomatous cell-mediated immunity. However, factors generated within the granuloma downregulate the antigen presenting function of DC by Day 3 in this experimental model.
Iyonaga
Kazuhiro
K
Department of Pathology, Massachusetts General Hospital, Boston 02129-2000, USA.
McCarthy
Karin M
KM
Schneeberger
Eveline E
EE
D000818:Animals; D001483:Base Sequence; D016207:Cytokines / Q000235:genetics; D017931:DNA Primers; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D006099:Granuloma / Q000276:immunology*; D017403:In Situ Hybridization; D016167:Integrin alphaXbeta2 / Q000276:immunology; D008168:Lung / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D012333:RNA, Messenger / Q000235:genetics
D016207:Cytokines; D017931:DNA Primers; D016167:Integrin alphaXbeta2; D012333:RNA, Messenger