Residual oil fly ash worsens pulmonary hyperreactivity in chronic allergic mice.

BALB/c mice received saline (SAL groups) or ovalbumin (OVA groups) intraperitoneally (days 1, 3, 5, 7, 9, 11 and 13). After 27 days, a burst of intratracheal OVA or SAL (days 40, 43 and 46) was performed. Animals were then divided into four groups (N=8, each) and intranasally instilled with saline (SAL-SAL and OVA-SAL) or residual oil fly ash (SAL-ROFA and OVA-ROFA). 24h later, total, initial and difference resistances (Rtot, Rinit, Rdiff) and static elastance (Est) were measured. Lung responsiveness to methacholine was assessed as slope and sensitivity of Est, Rtot, Rinit, and Rdiff. Lung morphometry (collapsed and normal areas and bronchoconstriction index) and cellularity (polymorphonuclear, mononuclear and mast cells) were determined. OVA or ROFA similarly impaired lung mechanics and increased the amount of polymorphonuclear cells and collapsed areas. OVA-ROFA showed even higher hyperresponsiveness, bronchoconstriction and mast cell infiltration. Thus, we concluded that ROFA exposure may add an extra burden to hyperresponsive lungs.