PT - JOURNAL ARTICLE AU - Anna-Carin Olin AU - Spela Kokelj AU - Jörgen Östling TI - Activation of the cascade-system in small airways- a pilot study in asthma with small airway involvement AID - 10.1183/13993003.congress-2020.157 DP - 2020 Sep 07 TA - European Respiratory Journal PG - 157 VI - 56 IP - suppl 64 4099 - http://erj.ersjournals.com/content/56/suppl_64/157.short 4100 - http://erj.ersjournals.com/content/56/suppl_64/157.full SO - Eur Respir J2020 Sep 07; 56 AB - The interactions between innate and acquired immune system seem important in the patho-physiology of asthma, but has so far only been explored to a limited extent. The cascade system (complement-, coagulation- and kallekrein systems) constitute an important part of the innate host-defense system. We hypothesize that proteins belonging to cascade system in the lining fluid from small airways, are activated in asthma.Methods: 10 subjects with asthma and small airway dysfunction (SAD), as indicated by lung-clearance index LCI z-score >3, 10 subjects with asthma with normal LCI , and 10 healthy controls were examined with PExA® method which is based on the sampling of droplets in exhaled air, endogenously formed when small airways close and re-open. 240 ng of undiluted lining fluid were sampled and analyzed using the Somascan platform (SomaLogic Inc). Results are based on GLM statistics using Qlucore Omics Explorer software, the signal from each protein is centered around zero.Results: 38 proteins belonging to the cascade system were identified in the PEx samples. The relative abundance of five of those proteins differed between healthy and those with SAD, see examples in Figure 1.Fig 1. Box scatter plots; levels of a) Complement 1q receptor, b) Complement 4, c) Factor IX and d) Factor X.Conclusion: The cascade system in the lining fluid from small airways seem of high importance in asthma with small airway involvement.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 157.This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only).