The Effect of Desloratadine on Eosinophil/Basophil Progenitors and Other Inflammatory Markers in Seasonal Allergic Rhinitis: A Placebo-Controlled Randomized Study

• Published in: International Archives of Allergy and Immunology 2005-11, Vol.138 (3), p.209-216
• Main Authors: Cyr, Michael M., Hayes, Lisa M., Crawford, Lynn, Baatjes, Adrian J., Keith, Paul K., Denburg, Judah A.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Allergies; Basophils - drug effects; Biological and medical sciences; Clinical trials; Cytokines; Cytokines - analysis; Eosinophils - drug effects; Female; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Histamine; Histamine H1 Antagonists, Non-Sedating - administration & dosage; Histamine H1 Antagonists, Non-Sedating - pharmacology; Humans; Immunopathology; Leukocyte Count; Loratadine - administration & dosage; Loratadine - analogs & derivatives; Loratadine - pharmacology; Male; Medical sciences; Middle Aged; Nasal Lavage Fluid - immunology; Original Paper; Pollen - immunology; Rhinitis, Allergic, Seasonal - immunology; Stem Cells - drug effects
• ISSN: 1018-2438; 1423-0097; 1365-2567
• DOI: 10.1159/000088721

Background: Eosinophil/basophil (Eo/B) progenitors fluctuate in the peripheral circulation during seasonal allergen exposure in atopic subjects. Several drugs have been shown to modulate Eo/B progenitor levels in the peripheral blood but, to date, the possible effect of antihistamines on Eo/B progenitors has not been explored. Our objective was to evaluate whether the antihistamine desloratadine (DL) can modulate peripheral blood Eo/B progenitors or other markers of allergic inflammation. Methods: We performed a randomized double-blind placebo-controlled study on the effects of DL on peripheral blood Eo/B progenitors in subjects with symptomatic, seasonal allergic rhinitis during a ragweed pollen season. Forty-five subjects were randomized to treatment for 4 weeks with DL 20 mg daily or placebo. Results: The expected fall in the number of Eo/B progenitors from baseline to 2 weeks of treatment was seen in the placebo group [median drop of 1.0 colony-forming unit (CFU)/10 6 cells], and was greater than in the DL group (median drop of 0.0 CFU/10 6 cells) (p = 0.013). The change in histamine concentration per colony from baseline to 2 weeks of treatment was lower in the DL group (median decrease of 6.1 pg/colony) compared to placebo (median increase of 1.8 pg/colony) (p = 0.01). An increase in the nasal lavage eotaxin concentration from baseline to 4 weeks of treatment was statistically significant in the placebo group but not in the DL group. Eo/B CFU were not affected by varyingin vitro concentrations of DL. Conclusion: These results suggest that DL can modulate aspects of allergic inflammation in vivo through mechanisms other than simple blockade of H 1 histamine receptors.