Activated Interferon‐γ‐Positive T Lymphocytes and Cytokine Signatures in Patients With Postinfectious Cough

ABSTRACT Postinfectious subacute cough (PISC) and postinfectious chronic cough (PICC) are triggered by respiratory infections, which induce adaptive immunity. The expression of T‐lymphocyte subsets and cytokine signatures remains elusive in these patients. Here, we recruited 40 healthy controls, 64 PICC patients, 65 PISC patients, and 20 recovered individuals with postinfectious subacute cough (R‐PISC). As cough and airway inflammation resolved in R‐PISC subjects, sputum lymphocytes dropped substantially. Both PICC and PISC patients had an increase in blood activated interferon‐γ (IFN‐γ) + T‐lymphocytes, which were decreased in R‐PISC subjects. Elevated cough sensitivity, higher proportions of activated IFN‐γ + T‐lymphocytes, and CD8 + /CD4 + T‐lymphocyte ratios, as well as elevated concentrations of uric acid, IFN‐γ, tumor necrosis factor‐α (TNF‐α), IFN‐α, IFN‐β, and interleukin‐10 in sputa, were observed in PICC and PISC patients but normalized in R‐PISC subjects. Correlation analyses and logistic regression models identified activated IFN‐γ + T‐lymphocytes and these cytokines in sputa as biomarkers for predicting cough risk. PICC patients exhibited greater cough severity, elevated activated IFN‐γ + T‐lymphocytes, and TNF‐α concentrations in sputa compared to PISC patients. Overall, postinfectious cough patients exhibit airway inflammatory signatures characterized by activated IFN‐γ + T‐lymphocytes and elevated levels of IFN‐γ, TNF‐α, IFN‐α, IFN‐β, and interleukin‐10, which are valuable for effective treatment options.