Effect of Diesel Exhaust on Immune Responses in C57BL/6 Mice Intranasally Immunized with Pollen Antigen

To investigate the effect of diesel exhaust or particle-free diesel gas on immune responses in IgE low responder mice, C57BL/6 mice immunized intranasally with sugi basic protein were exposed to diesel exhaust or diesel gas components. We evaluated the changes in lymphocyte subpopulations, cell proliferation, chemokine production of cervical lymph nodes cells, and antigen-specific-antibody levels in plasma. Exposure to diesel gas decreased the percentage of CD4+ and TCR-β+ T cells of cervical lymph nodes from immunized mice. Culture supernatants of cervical lymph nodes cells from diesel gas-exposed mice had significantly increased levels of macrophage inflammatory protein-1α and thymus and activationregulated chemokine, but exposure to diesel exhaust did not affect it. Antigenspecific IgG2a titers in plasma were significantly enhanced after their exposure to diesel exhaust or gas. In contrast, exposure to diesel exhaust or gas markedly decreased antigen-specific IgG1 titers in immunized mice. These facts indicate that concurrent exposure to allergen and diesel exhaust or diesel gas modulates chemokine production in cervical lymph nodes cells and antibody production in plasma differentially.