Allergen challenge causes inflammation but not goblet cell degranulation in asthmatic subjects.

BACKGROUND

An allergen challenge to the airways of sensitized mice causes eosinophilic airway inflammation and degranulation of goblet cells, which lead to airway obstruction. However, whether allergen challenge causes a similar pattern of airway inflammation and goblet cell degranulation in human beings is unknown.

OBJECTIVE

The purpose of this study was to determine whether allergen challenge increases airway inflammatory cells and causes goblet cell degranulation in human subjects with asthma.

METHODS

In bronchial biopsy specimens taken from 8 asthmatic subjects at 1 and 24 hours after allergen challenge, we measured eosinophil and neutrophil numbers as indicators of inflammation. We also measured goblet cell mucin stores and the amounts of secreted mucin in bronchial lavage as indicators of goblet cell degranulation.

RESULTS

Airway eosinophil numbers at both 1 and 24 hours after allergen challenge were twice as high as those after diluent challenge. Changes in neutrophil numbers were smaller and statistically insignificant. Goblet cell mucin stores measured in tissue stained with alcian blue/periodic acid-Schiff did not decrease significantly from baseline to 1 hour and actually tended to increase at 24 hours. This increase was significant in the subgroup of subjects with normal stored mucin levels at baseline. Mucin-like glycoprotein concentrations in bronchial lavage did not change significantly at either time point.

CONCLUSION

Although allergen challenge in asthmatic subjects increases airway eosinophil numbers as early as 1 hour after challenge, this inflammatory response does not cause goblet cell degranulation. In fact, in subjects with normal baseline mucin stores, allergen challenge increases goblet cell mucin stores.