Organic extract of diesel exhaust particles stimulates expression of Ia and costimulatory molecules associated with antigen presentation in rat peripheral blood monocytes but not in alveolar macrophages.
We hypothesized that diesel exhaust particles (DEP) induce the activation of antigen-presenting cells (APC) in lung. The present study was designed to clarify the following about DEP: (1) whether it affects the expression of Ia and B7 molecules in alveolar macrophages (AM) as a mature cell or in peripheral blood monocytes (PBM) as an immature cell, (2) if it affects the antigen-presenting (AP) activity of PBM, (3) what component of DEP is responsible for the effects, and (4) whether the effect of DEP is related to oxidative stress. DEP was extracted with methylene chloride. Cells were exposed to whole DEP, organic extract, or residual particles for 24 h. Cell-surface molecules were measured by flow cytometry. AP activity was assessed by antigen-specific T cell proliferation. Whole DEP or organic extract significantly increased the expression of Ia and B7 molecules on PBM but not on AM. No significant effect of residual particles was observed. A low concentration of organic extract also increased the AP activity of PBM. When the induction of an antioxidative enzyme was assessed, heme oxygenase-1 protein was found to be significantly increased by exposure to whole DEP, and the organic extract was more effective than the residual particles. Furthermore, the organic extract-induced expression of Ia antigen on PBM was reduced by the addition of an antioxidative agent. These results suggest that DEP may act on immature APC and enhance their AP activity and that the action contributing to oxidative stress may be mediated by organic compounds of DEP.
Koike
Eiko
E
Particulate Matter (PM2.5) and Diesel Exhaust Particles (DEP) Research Project, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan. ekoike@nies.go.jp
Kobayashi
Takahiro
T
D000818:Animals; D017951:Antigen Presentation / Q000187:drug effects* / Q000276:immunology; D018122:B7-1 Antigen / Q000378:metabolism; D051940:B7-2 Antigen / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D004797:Enzyme-Linked Immunosorbent Assay; D051547:Heme Oxygenase-1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000949:Histocompatibility Antigens Class II / Q000378:metabolism*; D016676:Macrophages, Alveolar / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D008297:Male; D009000:Monocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D010047:Ovalbumin / Q000276:immunology; D010316:Particle Size; D051381:Rats; D017208:Rats, Wistar; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D001335:Vehicle Emissions / Q000032:analysis / Q000633:toxicity*
D018122:B7-1 Antigen; D051940:B7-2 Antigen; D000949:Histocompatibility Antigens Class II; D001335:Vehicle Emissions; D010047:Ovalbumin; D051547:Heme Oxygenase-1