Background: The clinical benefit of the administration of aerosolised recombinant human DNase (rhDNase) on pulmonary function in patients with cystic fibrosis has already been demonstrated but the biochemical action of rhDNase on DNA in bronchial secretions in vivo has not yet been investigated.
Methods: Sputum was collected from 135 patients with cystic fibrosis before and during treatment with aerosolised rhDNase and examined to ascertain DNA concentration and length by colorimetric assay and densitometry of gel separated DNA.
Results: Treatment with rhDNase reduced the concentration and the size of extracellular DNA in the sputum. The median interquartile range of DNA length decreased from 0.5-2.6 kbp before treatment to 0.3-1.0 kbp during treatment.
Conclusions: rhDNase was delivered to the secretions and was enzymatically active in vivo.