Lipid-laden bronchoalveolar macrophages in asthma and chronic cough

The presence of lipids in alveolar macrophages (AMs) may impair their phagocytic response, and determine airway inflammation and obstruction.

To determine the factors such as severity of asthma, chronic cough, airway inflammation and obesity that may influence the presence of lipids in lung macrophages.

Bronchoalveolar lavage fluid (BALF) was obtained from 38 asthmatics (21 severe and 17 mild/moderate), 16 subjects with chronic cough and 11 healthy control subjects. The presence of lipids in macrophages was detected using an Oil-red-O stain and an index of lipid-laden macrophages (LLMI) was obtained.

LLMI scores were higher in healthy subjects (median 48 [IQR 10-61]) and the severe asthma group (37 [11.5-61]) compared to mild/moderate asthmatics (7 [0.5-37]; p < 0.05 each). Subjects reporting a history of gastro-oesophageal reflux disease (GORD) had higher LLMI values (41.5 [11.3-138] versus 13 [0-39.3], p = 0.02). There was no significant correlation between LLMI and chronic cough, BAL cell differential counts, FEV1, FEV1/FVC or body mass index (BMI).

The reduced LLMI in mild/moderate asthma may be related to lower incidence of GORD. However, this was not related to the degree of airflow obstruction, obesity or airway inflammation.