You are here:
TIMING OF DIESEL PARTICLE INSTILLATION AND MAGNITUDE OF DOSE INFLUENCE THE SEVERITY OF ALLERGIC AIRWAYS RESPONSES IN MICE
Citation:
FARRAJ, A., N. HAYKAL-COATES, J. R. LEHMANN, B. J. SUTHERLAND, AND S. H. GAVETT. TIMING OF DIESEL PARTICLE INSTILLATION AND MAGNITUDE OF DOSE INFLUENCE THE SEVERITY OF ALLERGIC AIRWAYS RESPONSES IN MICE. Presented at American Thoracic Society Annual Meeting, San Francisco, CA, May 18 - 23, 2007.
Description:
Exposure to diesel exhaust particulates (DEP) arising from the combustion of diesel fuel exacerbates asthma. Several studies have shown that particulate and allergen co-exposure leads to an exacerbation of the hallmark features of allergic airways disease relative to allergen exposure alone. It is unclear, however, whether this exacerbation is influenced by the timing of DEP exposure with respect to allergen priming and elicitation and/or DEP dose. The purpose of this study was to assess the effects of intranasal instillation of 10 or 50 µg DEP 4 hours before sensitization and/or 50 or 150 µg DEP 4 hr before challenge. Instillation of 50, but not 10, µg of DEP before ovalbumin (OVA) sensitization increased methacholine (MCH)-induced ventilatory responses. Instillation of 150, but not 30, µg DEP before allergen challenge also increased ventilatory responses. Exposure to DEP before both sensitization and challenge, however, did not elicit a significant increase in ventilatory responses. Instillation of 10, but not 50 ,µg of DEP before sensitization enhanced the OVA-induced increase in macrophages in the lung lining fluid. Instillation of 50, but not 150, µg of DEP before challenge enhanced the OVA-induced increased in macrophages in the lung lining fluid. There was no significant effect of DEP instillation on cellular infiltration into the lung when DEP at either concentration was administered before both sensitization and challenge. The data suggest that lower doses of DEP influence inflammatory cell infiltration to a greater degree than higher doses and vice versa with respect to ventilatory responses. In addition, exposure to DEP before allergen priming or elicitation may be more likely to enhance inflammatory and ventilatory responses than exposure during both periods (This abstract does not reflect EPA policy).