The Effects of Inhaled Budesonide on Circulating Eosinophil Progenitors and Their Expression of Cytokines after Allergen Challenge in Subjects with Atopic Asthma

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Abstract
Allergen inhalation by dual responder subjects with atopic asthma is associated with an increase in circulating eosinophil/basophil col- ony-forming units (Eo/B CFU) and granulocyte-macrophage colony- stimulating factor (GM-CSF) immunolocalization in Eo/B colony cells grown in vitro. The current study examined the effect of the inhaled corticosteroid, budesonide, on the number 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 vitro. Sixteen subjects with mild atopic asthma were treated for either 7 or 8 d with 200 m g inhaled budesonide or pla- cebo twice a day. Peripheral blood was collected before and 24 h af- ter allergen inhalation challenge and nonadherent 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 circulating eosinophils (4.0 6 0.4 3 10 5 /ml versus 6.5 6 0.7 3 10 5 /ml, p 5 0.0001), circulating Eo/B CFU (12.4 6 2.3/10 6 NAMC versus 18.8 6 4.6/10 6 NAMC, p 5 0.05), and immunolocal- ization of GM-CSF in Eo/B colony cells (11.8 6 1.9% positive versus 18.0 6 2.2%, p 5 0.01) but not immunolocalization of IL-5 (7.9 6 1.4% versus 4.5 6 0.6%, p . 0.05). Inhaled budesonide at- tenuated the number of allergen-induced circulating eosinophils and their progenitors grown in the presence of GM-CSF, which may partially be a result of regulating eosinophil progenitor ex- pression of the autocrine growth factor GM-CSF.

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