Endoscopic sampling of airway and lymphatic tissue for evaluation of immunity response after influenza vaccination – a protocol from the VAXXAIR project

<bold>Background and Aim:</bold> Less is known about post-vaccine mucosal airway immunity response and optimal sampling sites for its evaluation. In the VAXXAIR project, we aim to examine immunity responses by sampling airway mucosa and adjacent lymphatic tissue after nasal or intramuscular administration of influenza vaccine. We provide the protocol for endoscopic sampling. <bold>Methods:</bold> Healthy individuals, 18-49 years, under sedation and topical anesthesia. <bold>Bronchoscopy:</bold> 1. Bronchosorption strips are deployed on the mucosa of the main carina. 2. Bronchial brushings from the left or right lower lobe (LLL/RLL) 3. Bronchial mucosal forceps biopsies from segmental carinas from LLL/RLL 4. Bronchoalveolar lavage from the middle lobe or lingula. <bold>Endobronchial ultrasound (EBUS):</bold> 5. Fine needle aspiration (FNA) from ultrasonographic (US) visible paratracheal or subcarinal lymph nodes 6. FNA from US visible palatine tonsils <bold>Results:</bold> We performed 14 endoscopies in 11 persons (age 22-26; 64% male) in the pilot phase without any complications. Mean procedure time was 51 min. (38-66). Mean lymph node size was 4 mm and visible tonsils varied between 5-10 mm. <bold>Conclusion:</bold> Extensive sampling from multiple anatomic localizations requires rigorous optimization of sampling timing, technique and handling. We have refined the protocol during the pilot phase, and we consider the protocol ambitious, exploratory, safe and feasible. The project will contribute to the understanding of immunological responses in the airway mucosa after influenza vaccines and potentially lay foundation to an airway sampling model for testing new vaccines against respiratory infections in the future.