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 enzyme inhibitors
has not been clearly described. We investigated the possibility that a
chronic nonproductive cough without other potential causes is
associated with airway inflammation, and if this is so, what the
relationship might be between this inflammation and the possible
etiology of the cough.
Subjects: Twenty-five adults
with chronic nonproductive cough as an isolated 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 biopsies were performed. In the bronchial
biopsies, the patients were divided into the following two subgroups:
21 patients who were infiltrated with eosinophils vs the healthy
control group (median, 12.0 vs 0.0 cells/mm2, respectively;
p < 0.01); and 4 patients who were infiltrated with lymphocytes vs
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-infiltrated patients received diagnoses of
cough-variant asthma, and the other 16 patients received diagnoses of
eosinophilic bronchitis. In the lymphocyte-infiltrated group, all four
patients received diagnoses of lymphocytic bronchitis.
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 bronchitis.