INCREASED IMMUNE AND INFLAMMATORY RESPONSES TO DUST-MITE ANTIGEN IN RATS EXPOSED TO 5 PPM NO2

Immune hypersensitivity to house dust mite antigen (HDM) is a frequent cause of respiratory allergy. The objective of this study was to dete rmine whether exposure to NO2, a common indoor air pollutant, modulate s immune responses to HDM and influences immune-mediated lung disease. Brown Norway rats were immunized ip with 100 mu g semipurified antige n and Bordetella pertussis adjuvant and challenged 2 weeks later with an intratracheal injection of 50 mu g of a crude antigen preparation. Exposure to 5 ppm NO2 for 3 hr after both immunization and challenge p rocedures resulted in significantly higher levels of antigen-specific serum IgE, local IgA, IgG, and IgE antibody than air controls, and inc reased numbers of inflammatory cells in the lungs. Lymphocyte responsi veness to antigen in the spleen and MLN was also significantly higher in NO2-exposed animals. These data show that exposure to a common air pollutant can upregulate specific immune responses and subsequent immu ne-mediated pulmonary inflammation. (C) 1996 Society of Toxicology