The adjuvant activity of pyrene in diesel exhaust on IgE antibody production in mice.

In this communication, it is shown that pyrene has an adjuvant activity on IgE antibody production when mice are immunized by an intraperitoneal injection of ovalbumin (OA) or Japanese cedar pollen allergen (JCPA) with pyrene. The effects of pyrene on IgE antibody production in mice were investigated to clarify the relation between pollen allergy and the adjuvanticity of the chemical compounds contained in diesel-exhaust particulates (DEP). In the first experiment, three groups of mice were immunized intraperitoneally six times at 2-week intervals with 1 microgram of OA alone, 1 microgram of OA plus 1 mg of pyrene, and 1 microgram of OA plus 1 mg of DEP, respectively. The IgE antibody responses to OA in mice immunized with OA plus pyrene or OA plus DEP were extremely enhanced as compared with those in mice immunized with OA alone, and the highest responses were observed in mice immunized with OA plus DEP. In the second experiment, mice were immunized with 10 micrograms of JCPA alone or 10 micrograms of JCPA plus 5 mg of pyrene in the same way. The IgE antibody responses to JCPA in mice immunized with JCPA plus pyrene were higher than those in mice immunized with JCPA alone. The intraperitoneal macrophages of the mice also clearly stimulated in vitro by pyrene on chemiluminescence assay. These results suggest that pyrene contained in DEP acts as an adjuvant in IgE antibody production when mice are immunized with antigens.