Development of bone marrow eosinophilia in mice induced by Aspergillus fumigatus antigens

A model of allergic bronchopulmonary aspergillosis (ABPA) developed by exposing mice to Aspergillus fumigatus antigen (Af) exhibits peripheral blood (PB), lung, and bone marrow (BM) eosinophilia. Because the BM is a site of eosinophilopoiesis, we have investigated the role of Af in the induction of this process in the BM. Groups of mice were exposed intranasally (i.n.) or intraperitoneally (i.p.) to Af. BM cells from mice were cultured with either Af or allogenic spleen cell supernatant stimulated with Af. Eosinophil counts in different lymphoid compartments, eosinophil peroxidase (EPO), and mRNA for cytokines and IgE in BM cells were studied. Results indicate that the eosinophil numbers were significantly elevated in PB and BM of all Af-exposed mice. Lung lavage eosinophils increased only in the i.n. group. Af induced EPO activity only in BM cultures from Af-exposed mice. The EPO activity was further enhanced by supernatants from spleen cells from Af-exposed mice. mRNA transcription of IL-3 and IL-5 were measurable in BM cells of the ip exposed mice. These findings suggest that Af mediates eosinophil development in BM of mice and this process is promoted by hematopoietic factors generated within the BM and in other lymphoid tissue such as the spleen.