The effects of inhaled budesonide on circulating eosinophil progenitors and their expression of cytokines after allergen challenge in subjects with atopic asthma

Allergen inhalation by dual responder subjects with atopic asthma is associ ated with an increase in circulating eosinophil/basophil colony-forming uni ts (Eo/B CFU) and granulocyte-macrophage colony-stimulating factor (CM-CSF) immunolocalization in Eo/B colony cells grown in vitro. The current study examined the effect of the inhaled corticosteroid, budesonide, on the numbe r of allergen-induced circulating eosinophils and Eo/B CFU, and immunolocal ization of GM-CSF and interleukin-5 (IL-5) in Eo/B colony cells grown in vi tro. Sixteen subjects with mild atopic asthma were treated for either 7 or 8 d with 200 mug inhaled budesonide or placebo twice a day. Peripheral bloo d was collected before and 24 h after allergen inhalation challenge and non adherent mononuclear cells (NAMC) were grown in methylcellulose culture. Eo /B CFU were enumerated after 14 d in culture, and prepared on slides for im munocytochemistry. Budesonide attenuated the allergen-induced increase in c irculating eosinophils (4.0 +/- 0.4 x 10(5)/ml versus 6.5 +/- 0.7 x10(5)/ml , p = 0.0001), circulating Eo/B CFU (12.4 +/- 2.3/10(6) NAMC versus 18.8 +/ - 4.6/10(6) NAMC, p = 0.05), and immunolocalization of CM-CSF in Eo/B colon y cells (11.8 +/- 1.9% positive versus 18.0 +/- 2.2%, p = 0.01) but not imm unolocalization of IL-5 (7.9 +/- 1.4% versus 4.5 +/- 0.6%, p > 0.05). Inhal ed budesonide attenuated the number of allergen-induced circulating eosinop hils and their progenitors grown in the presence of GM-CSF, which may parti ally be a result of regulating eosinophil progenitor expression of the auto crine growth factor GM-CSF.