Effect of diesel exhaust particles and their components on the allergen-specific IgE and IgG1 response in mice

Increased antigen-specific IgE expression is a hallmark of the allergic res ponse in mice. IgG1 may also be involved. Co-injection of mice with diesel exhaust particles (DEP) and ovalbumin three times over a 2 week period lead to a rapid and marked elevation of ovalbumin-specific IgE, IgG1 and also I gG1a, compared with ovalbumin alone. When DEP were injected 1 day before or after ovalbumin on each occasion, their adjuvant effect was considerably m uted, suggesting that the adjuvant effect of DEP is short-lived, or that a physical interaction between ovalbumin and DEP is required. DEP were extrac ted with methylene chloride. Both the resulting core carbon particles and t he organic extract enhanced ovalbumin specific IgE and IgG 1 levels. Thus t he adjuvant effect of DEP in this model is due both to the physical and the chemical attributes of the particles. The trycyclic hydrocarbons phenanthe ne (the most prevalent polycyclic aromatic hydrocarbon in DEP) and anthrace ne were both capable of enhancing antigen-specific IgE and IgG1 production. The phenolic antioxidant, butylated hydroxyanisole, which can affect gene expression via the antioxidant responsive element (ARE), had a lesser effec t. Two agonists for the aryl hydrocarbon receptor, 3-methychloranthrene and 2,3,7,8-tetrachlorodibenzo-p-dioxin, either were without effect or suppres sed the response, suggesting that DEP adjuvancy may not br mediated by this receptor. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.