2026-11-04 カロリンスカ研究所（KI）
スウェーデンのカロリンスカ研究所などの研究チームは、呼気に含まれる微小粒子を採取し、肺の小気道に存在するウイルス特異的抗体を非侵襲的に測定する方法を開発した。従来、鼻腔の抗体測定は比較的容易である一方、肺の奥にある下気道の免疫状態を調べるには、気管支鏡などの侵襲的な検査が必要だった。今回、研究チームは呼気中粒子採取技術「PExA（Particles in Exhaled Air）」を利用し、呼吸器の末梢気道を覆う液体に由来する微小粒子を回収して分析した。28人の参加者を対象に、血液、鼻腔分泌物、呼気試料を比較した結果、SARS-CoV-2、インフルエンザウイルス、RSウイルス（RSV）に対するIgAおよびIgG抗体の検出に成功した。肺のIgG抗体量は血液中の濃度と強く関連する一方、IgAは局所的な粘膜免疫反応を反映する傾向が確認された。本技術は、感染やワクチン接種後の肺の免疫応答を継続的に調べるほか、粘膜ワクチンや予防的抗体療法の評価への応用が期待される。
Illustration: Lovisa Thålin
＜関連情報＞
- https://news.ki.se/lung-antibodies-can-be-measured-in-exhaled-breath
- https://www.thelancet.com/journals/ebiom/article/PIIS2352-3964(26)00422-6/fulltext
論文タイトル Non-invasive quantification of lower airway antigen-specific antibodies using exhaled breath particles – an observational proof-of-concept study
Katherina Aguilera ∙ Andreas Hober ∙ Nina Greilert Norin ∙ Mina Mahdi ∙ Vera C. Stäheli ∙ Iryna Kolosenko ∙ et al.
eBioMedicine Published: November 2, 2026
DOI:https://doi.org/10.1016/j.ebiom.2026.106538
Summary
Advancements in mucosal vaccine development highlight the urgent need for practical methods to assess immune responses in both upper and lower airways. Although nasal sampling is increasingly standardised, a non-invasive technique for directly assessing antigen-specific antibodies in the distal airways has been lacking.
We used Particles in Exhaled Air (PExA), a non-invasive method capturing aerosolised respiratory tract lining fluid (RTLF) from the distal airways, to quantify antigen-specific IgA and IgG. Antibodies were measured in paired serum, nasal secretions, and PExA samples from 28 healthcare workers during spring 2025, including 18 with RT-qPCR-confirmed SARS-CoV-2, influenza A (H1N1), or respiratory syncytial virus (RSV) infection.
Antigen-specific IgA and IgG measurements in PExA samples showed low variability (median CVs: spike-IgA 3.7%, H1-IgA 7.2%, RSV pre-F-IgA 5.3%). Strong correlations (Spearman’s rho >0.85, p < 0.0001) were observed between PExA and serum IgG, which may be consistent with a systemic contribution to lower-airway IgG levels. In contrast, IgA correlations were more modest, which may reflect local IgA production in the lungs. IgG and IgA correlated between PExA and nasal secretions, while the IgA/IgG ratio was higher in nasal secretions (median 5.0 vs 0.6, p < 0.0001), consistent with expected isotype distribution in upper and lower airways.
This study demonstrates the feasibility of non-invasive measurement of antigen-specific antibodies in the lower airways. Our approach proposes a framework for assessing lower-airway immunity and supporting next-generation mucosal vaccine development.
This study was funded by the European Research Council, the Swedish Society for Medical Research, and the Knut and Alice Wallenberg Foundation.
