IL4 and Increased total eosinophil count: We examined how diesel exhaust particles (DEP) enhance house-dust-mite (HDM) inflammatory responses within the lung and characterised potential mechanisms that may contribute to enhanced type 2 (T2) inflammatory responses.<h4>Results</h4>In mice subjected to repeated intranasal exposures, DEP alone had modest effects, whereas DEP + HDM markedly increased type-2 inflammatory indicators (Serum IgE; Airway Il13, Il4 & Tslp) and eosinophilia alongside expansion of Th2 cells.