Cystic fibrosis: effects of serum factors on mucus secretion.

The effects of serum from children with cystic fibrosis and from normal 
children on the mucus-secreting, ciliated epithelium have been investigated in vitro 
using explanted tissue from rabbit lung. By optical and scanning electron 
microscopy, a sequence of structural changes is observed after incubation with 
cystic fibrosis serum; this sequence does not occur with normal serum. 
The earliest changes involve swelling of the goblet cells, with subsequent 
discharge of mucus onto the epithelial surface. This is followed by 
disruption of the normally rapid and synchronized ciliary activity. Mucus gradually 
extends over the surface entangling cilia. Finally, some shedding of ciliated 
cells occurs from the epithelium. These findings suggest that factors in 
cystic fibrosis serum cause discharge of mucus leading to a disturbance 
of the normal ciliary activity in the rabbit lung. It is 
postulated that such changes result in dysfunction of the mucociliary clearance 
mechanism and that this dysfunction may be a contributory factor to 
the pathogenesis of lung disease. 