A simple breath into a handheld-style instrument may one day replace bronchoscopy for measuring antibodies deep in the lungs, according to a study by researchers at Karolinska Institutet and Danderyd Hospital, News55 reported. The findings, published in the journal eBioMedicine, show that virus-specific antibodies can be detected in particles exhaled from the smallest airways.
Airway mucous membranes contain antibodies that help block respiratory viruses like flu, SARS-CoV-2 and RSV. While nasal antibodies are relatively easy to measure, sampling farther down in the lungs normally requires bronchoscopy, in which an instrument is passed down the airways. In the new study, the researchers instead used a method called PExA — Particles in Exhaled Air — in which a person breathes out into a device that captures tiny particles carried from the fluid lining of the lungs’ smallest airways, Forskning.se reported.
28 Participants Breathed Into the Instrument
The study included 28 participants from the COMMUNITY study at Danderyd Hospital, 18 of whom had recently had a respiratory infection. Researchers analyzed blood, nasal lining and exhaled breath for antibodies against SARS-CoV-2, influenza and RSV, according to Forskning.se.
The team measured two antibody types, IgA and IgG, in the samples from the small airways. IgG levels in the lungs largely tracked blood levels, while IgA appeared to be produced mainly on site in the airways.
“Participants only need to breathe into an instrument,” said Katherina Aguilera, a doctoral student and the study’s first author, according to News55. Because the sampling is so simple, she said, it can be repeated to follow the immune system over time.
What the Method Could Track
She noted that immune defense deeper in the airways matters for fighting infections and protecting against severe disease.
The researchers said the approach could eventually be used to study how lung immunity changes after infections or vaccinations, and to evaluate vaccines and preventive antibody treatments aimed at the airway lining. They cautioned that this is a first study with few participants and that the method needs evaluation in larger studies, Forskning.se reported.
Questions Readers Ask About the Breath-Test Study
How many people took part, and how many had been sick? The study had 28 participants from the COMMUNITY study at Danderyd Hospital, and 18 of them had recently had a respiratory infection.
Which viruses were the antibodies measured against? The researchers measured antibodies against SARS-CoV-2, influenza and RSV in blood, nasal samples and exhaled breath.
Why does the IgA finding matter? IgG levels in the lungs mostly matched blood levels, but IgA appeared to be produced locally in the airways, showing the two antibody types behave differently in the lower respiratory tract.
Where was the study published? The paper, “Non-invasive quantification of lower airway antigen-specific antibodies using exhaled breath particles,” was published in eBioMedicine.
This is the first study to measure antibodies against specific respiratory viruses in exhaled breath, and the researchers stress it must be confirmed in larger trials before the method can be used to monitor immunity over time.