Immune responses to Aspergillus antigen in IL-(4)-/- mice and the effect of eosinophil ablation

Background: Exposure to Aspergillus fumigatus allergens results in enhanced total serum IgE and peripheral blood eosinophils in mice. The associated p ulmonary inflammation and immunologic responses are comparable to those det ected in human allergic bronchopulmonary aspergillosis. Allergen-induced cy tokines are thought to regulate the inflammatory and immune responses in th ese animals. Methods: In the present study, we exposed C57BL/6 and BALB/c mice to A. fum igatus antigen. Both wild-type and IL-4 knockout phenotypes of animals of b oth strains were used. Some animals were also treated with anti-IL-5 or ant i-IFN-gamma. Total serum IgE, Aspergillus species IgG subclass, peripheral blood eosinophils, and lung histology were studied. Results: The results demonstrate similar lung inflammation in all wild-type and IL-4-/- animals exposed to A. fumigatus antigen. Similarly, in spite o f the diverse immune response produced by the anticytokine treatment, no ma jor differences were detected among any of the animal groups studied. Conclusions: It can be concluded that A. fumigatus exposure in an immunolog ically unaltered host is predominantly of a Th2 type, and that depletion of the Th2 cytokine leads to a similar lung inflammation but with a character istic Th1 response, suggesting that the pathogenesis of allergic aspergillo sis is the result of multiple induction pathways.