THE ADJUVANT ACTIVITY OF DIESEL EXHAUST PARTICLES AND CARBON-BLACK ONSYSTEMIC IGE PRODUCTION TO OVALBUMIN IN MICE AFTER INTRANASAL INSTILLATION

The adjuvant activity of diesel exhaust particles (DEP) on systemic IE E production to ovalbumin (OA) was studied in mice after intranasal ad ministration. The main purpose was to elucidate which part of the part icles was responsible for the effect, the carbon core and/or the adsor bed organic substances. Female Balb/cA mice were immunized with OA eit her alone or in combination with DEP or carbon black particles (CB), t he latter used as a surrogate for the non-extractable carbon core of D EP. Controls were given DEP, CB or buffer alone. The animals were immu nized four times. 1 and 2 weeks after the last immunization anti OA Ig E antibody in serum was analysed by enzyme linked immunosorbent assay (ELISA). An increased response to the antigen was observed in animals receiving OA together with DEP or CB, compared with animals receiving OA alone. The increased response was seen as both increased number of responding animals and increased serum anti OA IgE antibody. For OA DEP 37% of the animals showed a serum anti OA IEE response, whereas 22 % of the OA + CB animals and 10% of the OA animals responded. In concl usion, this work shows that not only DEP, but also CB have an adjuvant activity for specific IgE production after intranasal instillation. H owever, the activity of DEP may be more pronounced than that of CB. Th e results imply that both the organic matter adsorbed to DEP and the n on-extractable carbon core are responsible for the observed adjuvant e ffect. (C) 1997 Elsevier Science Ireland Ltd.