Association Between Respiratory Viral Infection and Peripheral T Lymphocyte Subsets in Elderly Patients With Acute...

Respiratory viral infections are increasingly recognized as important triggers of acute exacerbations in bronchiectasis (AEB); the virological profiles and immunological mechanisms in elderly patients remain poorly characterized.

A prospective cohort of 102 elderly bronchiectasis patients was followed for 12 months. Upon AEB occurrence, nasopharyngeal swabs were obtained for multiplex fluorescence quantitative PCR detection of eight respiratory viruses, while peripheral blood samples were analyzed for T lymphocyte subsets by flow cytometry. Clinical characteristics, inflammatory markers, and T cell subsets were compared between virus-positive and virus-negative groups at first AEB; ROC curve analysis evaluated the predictive value of T cell subsets for viral infection.

A total of 93 AEB episodes were captured from 68 patients during 12-month follow-up, with viruses detected in 54.8% (51 of 93) of episodes, influenza virus being the most common pathogen (24 of 51, 47.1%). Compared with the virus-negative group, the virus-positive group showed higher IL-6 and TNF-α and lower CRP and WBC levels (p < 0.05), higher sputum culture positivity with Haemophilus influenzae predominating, along with increased use of intravenous antibiotics and respiratory support, while quality of life, pulmonary function, and oxygenation remained comparable. The virus-positive group showed lower CD4⁺ T cell counts (431.28 ± 152.36 vs. 508.42 ± 158.94, p = 0.025) and CD4⁺/CD8⁺ ratios (1.41 ± 0.44 vs. 1.63 ± 0.49, p = 0.013).

Viral infections are frequent in elderly bronchiectasis patients with AEB and are characterized by reduced CD4⁺ T-cell counts, lower CD4⁺/CD8⁺ ratios, and heightened inflammatory responses, reflecting underlying age-related immune vulnerability.