ADJUVANT EFFECT OF RESPIRATORY IRRITATION ON PULMONARY ALLERGIC SENSITIZATION - TIME AND SITE DEPENDENCY

It has been suggested that airway irritation, by acting as an adjuvant , as well as producing damage, may be an important factor related to a sthma, The present study examined the window of time following acute u pper and lower airway irritant exposure to determine the period of inc reased risk of immunological sensitization. Brown Norway rats were exp osed to 87 ppm NO2 or 1000 ppm NH3 for 1 hr, A 30-min ovalbumin (OVA) exposure of 18.14 mu g/liter air was given at various times based upon the time course of irritant associated inflammatory response (either immediately prior to or 1 or 7 days after the irritant exposure), OVA- only, NO?only or NH3-only controls, and saline controls were also stud ied, Weekly booster exposures of OVA (or saline) were given, Circulati ng OVA-specific IgE, IgA, and IgG levels were quantified periodically during the 6 weeks of the study. Bronchoalveolar lavage (BAL) was also performed to examine the inflammatory response to allergic and irrita nt challenge, Significant increases in OVA-specific IgE, IgG, and IgA antibody titers were seen in rats given the sensitizing OVA exposure w ithin 1 day of the NO2, but not NH, exposures, Enhancement of cellular infiltrate in BAL was noted in groups given the sensitizing OVA expos ure within 1 day of the NO2 or NH3, It is concluded that the inflammat ory and immunological response to antigen exposure can be modified by the site of respiratory tract irritation and the relative times of irr itant and antigen exposure. (C) 1997 Academic Press.