¹University Medical Center Schleswig-Holstein, Department of Internal Medicine I, Division of Rheumatology, Kiel
²University Medical Center Schleswig-Holstein, Department of Internal Medicine I, Kiel
³German Institute for Aerospace Medicine (DLR), Köln

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Introduction: Nasal swabs have become widely recognised for their role in rapid diagnostic testing during the COVID-19 pandemic, but have recently emerged as a potentially valuable tool in immunological research as well [1]. Their usefulness in sampling immune responses in the upper respiratory tract (URT) offers new possibilities for investigating local immunological findings in chronic inflammatory disease of both the URT and in systemic inflammation. Mucosal findings can thus be compared with systemic findings in peripheral blood. This pilot study compares immune cell profiles obtained from both nasal swabs and peripheral blood of patients with chronic inflammatory airway diseases and healthy controls, focusing on mucosal and systemic immune signatures.

Methods: Patients with chronic respiratory disease and healthy volunteers performed four nasal swabs, followed by immune cell isolation from the collected samples. In parallel, peripheral blood mononuclear cells (PBMCs) were isolated. Flow cytometry was used to analyse immune cell subsets, particularly B cell subpopulations including plasma cells and T cell subpopulations.

Results: Immune cells were successfully isolated from both nasal swabs and blood. Nasal swabs revealed prominent populations of CD19 positive plasma cells, memory B cells and germinal centre B cells as well as T cell subsets such as Th1, Th2, Th17, Treg and follicular T cells. Preliminary data reveals distinct immune cell populations in blood and nasal samples, with follicular T cells being notably more prominent in nasal swabs (13.8% vs 45.5% of CD4+ cells). Furthermore 3.52% of nasopharyngeal B cells in patients with allergic rhinitis/asthma could be identified as plasma cells (PC, CD38+/CD27+) compared to 1.43% in healthy controls (preliminary data, n=3/group), while PC counts in blood were comparable.

Conclusion: To our knowledge, this is the first study comparing lymphocyte subsets from mucosal surfaces to blood subsets in chronic inflammation. Our data suggests nasal swabs represent a technically simple and minimally invasive method to analyse immune profiles, e.g. in the URT. This approach could help to characterise local immune responses in various chronic inflammatory conditions that involve mucosal tissues but are not primarily characterised by involvement of nasal mucosa. Further investigations with larger cohorts are warranted to validate and extend these findings.

Disclosures: The authors and I declare that the research was conducted in the absence of financial or commercial relationships that could be construed as a potential conflict of interest.

References

[1] Ramirez SI, Faraji F, Hills LB, Lopez PG, Goodwin B, Stacey HD, Sutton HJ, Hastie KM, Saphire EO, Kim HJ, Mashoof S, Yan CH, DeConde AS, Levi G, Crotty S. Immunological memory diversity in the human upper airway. Nature. 2024 Aug;632(8025):630-6. DOI: 10.1038/s41586-024-07748-8