Immunohistochemical distribution of surfactant apoprotein-A in congenital diaphragmatic hernia-II.

Morphometric analyses of the immunohistochemical expression of surfactant apoprotein A (SP-A) were carried out on the bronchioles of human congenital diaphragmatic hernia (CDH) neonates and then compared with those in a gestational and postnatal age-matched control group. There was no difference in SP-A expression between lung specimens of the control group and unaffected lungs in the CDH group. However, compared with both these lungs, the ipsilateral lungs of the CDH group showed a significant increase in SP-A expression, namely, the number of SP-A-positive cells per bronchiole, the number of SP-A-positive cells per unit perimeter of bronchiole, and the number of SP-A-positive cells per unit bronchiolar surface area. These results suggest that in lungs of CDH cases, especially ipsilateral lungs, there is a possible delay in the functional maturation or development of SP-A synthesis by the bronchiole, and this retardation may play a role in the postnatal respiratory insufficiency observed in CDH patients.