title: IgG subclass responses in experimental silicosis.
abstract: Silicosis is a crippling fibrotic lung disease induced by inhaling crystalline silica. In addition to fibrosis, silica inhalation by humans is associated with a number of immunological effects including increased levels of serum immunoglobulins (in particular IgG), increased prevalence of autoantibodies, and autoimmune disease. Recent studies using rodent models have shown that experimental silicosis is associated with a T-helper (TH)1 pattern of T-cell activation in the lungs and lung-associated lymph nodes after silica inhalation, which are also the sites of increased IgG production. We therefore hypothesized that the subclass distribution of IgG production occurring in experimental silicosis would suggest TH1 activation as the primary stimulus for IgG production. Using an ELISPOT assay, we found increased IgG-secreting spot-forming cells of all IgG subclasses in lung-associated lymph nodes taken from silica-exposed rats 3 to 4 months after aerosol exposure to silica. Neither TH1- nor TH2-dependent IgG subclass-secreting cells were selectively enhanced. Our findings suggest that TH1 activation alone does not account for increased production of IgG in experimental silicosis.
authors.affiliation: Health Effects Laboratory Division, Analytical Services Branch, National Institute for Occupational Safety and Health, Morgantown, WV 26505, USA. dqw4@cdc.gov
authors.forename: D N
authors.initials: DN
authors.lastname: Weissman
authors.forename: A F
authors.initials: AF
authors.lastname: Hubbs
authors.forename: S H
authors.initials: SH
authors.lastname: Huang
authors.forename: C F
authors.initials: CF
authors.lastname: Stanley
authors.forename: Y
authors.initials: Y
authors.lastname: Rojanasakul
authors.forename: J K
authors.initials: JK
authors.lastname: Ma
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D000395:Air Pollutants, Occupational / Q000633:toxicity*; D000818:Animals; D016175:B-Lymphocyte Subsets / Q000276:immunology; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology / Q000276:immunology; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay; D007074:Immunoglobulin G / Q000097:blood*; D008168:Lung / Q000187:drug effects / Q000276:immunology; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D012822:Silicon Dioxide / Q000008:administration & dosage / Q000633:toxicity*; D012829:Silicosis / Q000097:blood / Q000209:etiology / Q000276:immunology*; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D018417:Th1 Cells / Q000276:immunology
chemical_list: D000336:Aerosols; D000395:Air Pollutants, Occupational; D007074:Immunoglobulin G; D012822:Silicon Dioxide