Fig. 7:  The composition of the mucus differs according to the underlying pathology.  In COPD there are large amounts of mucins, less of plasma proteins, intermediate amounts of inflammatory cells, and contrary to, eg, cystic fibrosis, only small amounts of DNA.^[3]  This is the explanation for the unsuccessful use of recombinant human DNA in COPD patients.  On the right side of this Figure is a confocal micrograph of sputum from a patient with bronchitis.^[4]  On the left of this section the mucin polymers are stained with red with Texas red-UEA and compared to the green-stained DNA polymers [on the right] in the sputum of a patient with cystic fibrosis.