Adjuvant activity of diesel exhaust particulates (DEP) in production of anti-IgE and anti-IgG1 antibodies to mite allergen in mice.

The present study indicates that diesel exhaust particulates (DEP) and pyrene contained in DEP have an adjuvant activity on IgE and IgG1 antibody productions in mice immunized intranasally with a mite allergen. The effect of pyrene on IgE and IgG1 antibody productions in mice was investigated to clarify the relation between mite allergy and adjuvancy of the chemical compounds in DEP. Der f II, one of the major allergens of house dust mite (Dermatophagoides farinae), was used as a mite allergen. Mice were grouped, and immunized with 5 micrograms of Der f II alone, 5 micrograms of Der f II plus 200 micrograms of pyrene and 5 micrograms of Der f II plus 100 micrograms of DEP intranasally seven times at two week intervals. The separate groups of mice were also immunized with 10 micrograms of Der f II plus the same dose of adjuvants in the same way. The IgE antibody responses to Der f II in mice immunized with Der f II plus pyrene or Der f II plus DEP were markedly enhanced compared with those immunized Der f II alone. The anti-Der f II IgE antibody production increased with increasing the dose of Der f II from 5 micrograms to 10 micrograms in mice immunized with Der f II plus the same dose of adjuvants. The IgG1 antibody responses to Der f II in mice immunized with 10 micrograms of Der f II plus 200 micrograms of pyrene or 10 micrograms of Der f II plus 100 micrograms of DEP were extremely higher than those immunized with 10 micrograms of Der f II alone. In addition, when the peritoneal macrophages obtained from normal mice were incubated with pyrene or DEP in vitro, an enhanced interleukin-1 alpha production of the macrophages was observed. When the spleen lymphocytes obtained from the mice immunized with 10 micrograms of Der f II plus 100 micrograms of DEP or 10 micrograms Der f II plus 200 micrograms of pyrene were stimulated with 10 micrograms of Der f II in vitro, an enhanced IL-4 production of the lymphocytes was also observed compared with those immunized with Der f II alone. These results suggest that the adjuvancy of DEP and pyrene on the production of IgE and IgG1 antibodies to Der f II may be one of the factors responsible for an incidence of asthma caused by house dust mite.