Airway inflammation as an assessment of chronic nonproductive cough

Objectives: The possibility that a bronchial inflammatory process could be involved with a chronic nonproductive cough without other potential causes such as postnasal drip syndrome, bronchial asthma, gastroesophageal reflux, chronic bronchitis, bronchiectasis, or the use of angiotensin-converting e nzyme inhibitors has not been clearly described. We investigated the possib ility that a chronic nonproductive cough without other potential causes is associated with airway inflammation, and if this is so, what the relationsh ip might be between this inflammation and the possible etiology of the coug h. Subjects: Twenty-five adults with chronic nonproductive cough as an isolate d symptom over a 3-week period, and 5 healthy control subjects were studied . Measurements and results: Clinical assessments, cough scores, methacholine challenges, allergy skin prick tests, and bronchoscopies for bronchial biop sies were performed. In the bronchial biopsies, the patients were divided i nto the following two subgroups: 21 patients who were infiltrated with eosi nophils vs the healthy control group (median, 12.0 vs 0.0 cells/mm(2), resp ectively; p < 0.01); and 4 patients who were infiltrated with lymphocytes v s the healthy control group (median, 84.5 vs 22.0 cells/mm2, respectively; p < 0.01). With the methacholine challenge test, 5 of the 21 eosinophil-inf iltrated patients received diagnoses of cough-variant asthma, and the other 16 patients received diagnoses of eosinophilic bronchitis. In the lymphocy te-infiltrated group, all four patients received diagnoses of lymphocytic b ronchitis. Conclusions: These results suggest that a chronic nonproductive cough as an isolated symptom is associated with airway inflammation due to eosinophil and lymphocyte infiltration. The causes of the chronic nonproductive cough were eosinophilic bronchitis, cough-variant asthma, and lymphocytic bronchi tis.