title: Organic dust-induced activation, adhesion to substrate and expression of intercellular adhesion molecules in THP-1 monocytes.
abstract: Inhalation of organic dust in a swine confinement building induces systemic reactions, increased bronchial responsiveness and intense airway inflammation in previously unexposed, healthy subjects. These effects are self-limiting, but chronic respiratory symptoms are frequently observed in swine confinement workers. The present study was aimed at investigating organic dust-induced activation of the monocytic leukemia cell line, THP-1. Unstimulated THP-1 cells proliferate in suspension but cultivation for several days in medium with complete dust or 0.22-mu-filtered suspension, caused a subset of the THP-1 cells to adhere to the substratum. As assessed by transmission light- and indirect immunofluorescence microscopy, dust-stimulated adherent THP-1 cells adopted macrophage-like morphology and expressed vimentin. Intercellular adhesion molecule (ICAM)-1 was expressed in all dust-activated adherent cells, but only in 1% of the unstimulated cells in suspension. Sialoadhesin, a macrophage marker, was detected in dust-stimulated adherent THP-1 cells but not in the parental monocytes. Serum factors were required for the dust-induced expression of sialoadhesin, but not for adhesion to substrate or expression of ICAM-1. In addition, morphology and expression of vascular endothelial growth factor (VEGF) of dust-stimulated adherent cells equalled that of PMA-differentiated THP-1 cells, but the PMA-differentiated cells exhibited weak sialoadhesin labelling. In conclusion, exposure to organic dust from a swine confinement building activated a subset of THP-1 monocytes inducing expression of intercellular adhesion molecules, which are important in inflammation. The sustained adhesion to substrate indicates that organic dust from a swine confinement building may contain agents that prevent deactivation and detachment of the cells.
authors.affiliation: The National Institute of Environmental Medicine, Lung and Allergy Research, Karolinska Institutet, Box 287, SE-171 77 Stockholm, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Burvall
authors.forename: Lena
authors.initials: L
authors.lastname: Palmberg
authors.forename: Kjell
authors.initials: K
authors.lastname: Larsson
mesh_terms: D000395:Air Pollutants, Occupational / Q000494:pharmacology*; D000818:Animals; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004391:Dust; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D011971:Receptors, Immunologic / Q000378:metabolism*; D063267:Sialic Acid Binding Ig-like Lectin 1; D013552:Swine; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
chemical_list: D000395:Air Pollutants, Occupational; D016895:Culture Media, Serum-Free; D004391:Dust; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; C571166:SIGLEC1 protein, human; D063267:Sialic Acid Binding Ig-like Lectin 1; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D014746:Vimentin; D018799:Intercellular Adhesion Molecule-1