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.