MUC5AC and chronic obstructive pulmonary disease: Prior studies have examined subjects with mild airflow obstruction only,[7] and another examined those with CB only.[8] One study in advanced emphysema patients found no relationship between cough and sputum symptoms and degree of small airway mucus impaction,[11] and an established pathologic measure of mucous gland hyperplasia has little to no correlation with clinical symptoms.[12] We sought to quantify goblet cell density and mucin volume density in moderate to severe COPD subjects and in those with and without CB.