Presentations

Macrophages are diverse cell types in the rst line of anti-micro bial defense and according to subset they can promote or dampen in ammation. Only a limited number of primary models exist to study macrophage functions. Mouse bone marrow derived , M-CSF-induced macrophages (BMM) with a limited lifespan are the most common in vitro model. We developed a simple method yielding self-renewing, non-transformed, GM-CSF/STAT5-dependent macrophages (MPI cells) from mouse fetal liver. Unlike other types of primary macrophages, MPI cells from various wild type, gene-de cient or transgenic mice strains can be propagated inde nitely in unlimited quantities and can be easily manipulated genetically. MPI cells are highly sensitive to selected microbial agents, including LPS, lipopeptide, Mycobacterium tuberculosis, cord factor and adenovirus. In response to these stimuli they show a pattern of innate responses similar to alveolar macrophages (AM) but di erent from BMM. For example, MPI cells and AM induce a strong pro-in ammatory but no IL-10 response, whereas BMM mount a less pro-in ammatory but strong IL-10 response. Moreover, MPI cells show an as yet unknown regulation of IL-1α production upon LPS exposure, likely to play a key role in lung in ammation in vivo. Due to their easy handling and characteristic alveolar mac-rophage-like properties, the newly established MPI cell lines may become a useful tool in biomedical research and especially for the study of macrophage responses to airborne pathogens. Monophosphoryl lipid A (MPL) is described as a non-toxic TLR4 ligand, derived from Salmonella minnesota R595 (Re) lipopoly-saccharide (LPS) by chemical modi cation. MPL is clinically used as an adjuvant for cancer treatment (Ceravix®), hepatitis vaccination (Fendrix®), and allergen speci c immunotherapy (Pol-linex® Quattro). Nevertheless, reports on the mechanism of ad-juvant activity are limited. e aim of this study was to compare the immune modulating capacities of MPL and LPS in vitro. In both human and murine lung epithelial cell lines (LA-4, A549) LPS induced higher CCL2 secretion than MPL. In murine BM-derived myeloid dendritic cells (mDC), LPS and MPL stimulation resulted in the same cytokine secretion pattern (IL-1β, IL-6, IL-10 and TNF-α). At high concentrations of MPL, IL-1β secretion was 4-fold higher compared to LPS, whereas LPS stimulation resulted in higher secretion of IL-6, IL-10 and TNF-α, respectively. Moreover, stimulation with both adjuvants resulted in mDC activation characterized by CD40 and CD69 upregula-tion. Here LPS proved to be more potent than MPL (thresholds for mDC activation: MPL: 100 …