TF-IUPS160017 198..198 LETTER TO THE EDITOR Author’s response: Dysfunction of small airways and prevalence, airway responsiveness and inflammation in asthma: much more than small particle size of pet animal allergens Dear Editor, We read with interest the letter from Liccardi et al. about our article ‘New data analysis in a population study raises the hypothesis that particle size contributes to the pro-asthmatic potential of small pet animal allergens’ (1). We would like to thank them for comments and for pin-pointing some weaknesses. Small airways dysfunction can be considered as a distinct clinical phenotype, but we were not able to examine small airway functional impairment in our population with methods such as measurements of FEF25–75, impulse oscillometry, or inert gas washout. We can therefore not investigate the prevalence of this phenotype in our population, but we have no reason to believe that this phenotype was over-repre- sented in our study as these subjects were part of a popula- tion-based study. Furthermore, it is true that various outdoor air pollutants and cigarette smoke can interact with allergic sensitization and influence inflammation in airways. Unfortunately, we did not have available data about pollution, but smoking preva- lence was relatively low and our measurements were adjusted for smoking history. Allergenic sources others than cat and dog can under cer- tain circumstances release allergens in ‘respirable’ form. The amount of allergens in small particle fraction can vary consid- erably, at least for pollen (2,3). In our study only cat and dog sensitization was significantly associated with a higher preva- lence of asthma and more airway responsiveness, and airway and systemic inflammation. The above associations were not observed for other perennial allergens (mite, mold, and mice). So therefore it is unlikely that the associations noted for cat and dog sensitization are due only to continuous exposure. In a previous study (4) comparison of cat with mite allergens showed that the amount of Fel d 1 carried by smaller par- ticles is higher than that of Der p 2. We were able to demonstrate an association between sen- sitization to pet allergens and more inflammation, assessed both as FENO and S-ECP, and bronchial responsiveness, and therefore it is plausible that sensitization to small-sized pet- allergen-particles can have an impact in the development of asthma. However, our study was cross-sectional and this hypothesis cannot be tested, but we can only report these associations and acknowledge the limitation of our study and need for longitudinal studies. Disclosure statement The author reports no conflicts of interest. References 1. Patelis A, Dosanjh A, Gunnbj€ornsdottir M, Borres MP, H€ogman M, Alving K, et al. New data analysis in a population study raises the hypothesis that particle size contributes to the proasthamatic potential of small pet animal allergens. Ups J Med Sci. 2016;121:25–32. 2. Riediker M, Koller T, Monn C. Differences in size selective aerosol sampling for pollen allergen detection using high-volume cascade impactors. Clinical Exp Allergy. 2000;30:867–73. 3. Schappi GF, Suphioglu C, Taylor PE, Knox RB. Concentrations of the major birch tree allergen Bet v 1 in pollen and respirable fine par- ticles in the atmosphere. J Allergy Clin Immunol. 1997;100:656–61. 4. de Blay F, Heymann PW, Chapman MD, Platts-Mills TA. Airborne dust mite allergens: comparison of group II allergens with group I mite allergen and cat-allergen Fel d I. J Allergy Clin Immunol. 1991;88:919–26. Antonios Patelis Medical Sciences, Uppsala University, Respiratory, Allergy and Sleep Research, Uppsala, Sweden antonios.patelis@medsci.uu.se Received 18 March 2016; accepted 29 March 2016 � 2016 The Author(s). Published by Taylor & Francis. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. http://dx.doi.org/10.3109/03009734.2016.1173746 UPSALA JOURNAL OF MEDICAL SCIENCES, 2016 VOL. 121, NO. 3, 198 Author&hx2019;s response: Dysfunction of small airways and prevalence, airway responsiveness and inflammation in asthma: much more than small particle size of pet animal allergens Disclosure statement References