Expression of Clara cell 10-kDa protein (CC10) in congenital diaphragmatichernia

Clara cell 10 kDa protein (CC10) has been thought to be fairly specific to Clara cells and a major secretory protein that is both synthesized and rele ased from Clara cells. In the present study, morphometric analyses of the i mmunohistochemical expression of CC10 were carried out on the bronchioles o f human neonates with congenital diaphragmatic hernia (CDH) and then compar ed with morphometric analyses from a gestationally and postnatally age-matc hed control group in order to clarify the immaturity of Clara cells in CDH lungs. No difference was found in CC10 expression between the affected side and the unaffected side of the lungs in the CDH group. However, compared w ith the lungs of the control group, the CDH group showed a significant decr ease in CC10 expression, namely, the ratio of CC10-positive cells per bronc hiole, per unit perimeter of bronchiole, and per unit bronchiolar surface a rea. These results suggest that in the lungs of CDH cases, a possible delay in either functional maturation or the development of CC10 synthesis by th e bronchioles may exist, and this retardation of functional maturation of t he airway is also considered to play a role in the postnatal respiratory in sufficiency observed in CDH patients.