Alkaline phosphatase induction in cystic fibrosis fibroblasts [letter].

Lysosomal acid hydrolases and alkaline phosphatase cooperate in the intracellular digestion of 
natural polymers. A stimulus for the induction of these enzymes is 
the retention of any kind of polymer inside the cell. This 
stimulus is long-lasting and strong if polymers are intracellularly retained because 
of a lack of digestive enzymes. In previous papers it has 
been demonstrated that the alkaline phosphatase (AIP) induction with Tamm Horsfall 
glycoprotein discriminates between fibroblasts of CF homozygotes on the one hand 
and normals and CF carriers on the other hand, and a 
hypothesis has been proposed to explain these observations. As predicted, more 
efficient inducing mixtures have since been developed; these have been used 
in the present study. The first writer familiarized himself with ultramicrotechniques 
and then carried out double blind studies on 20 fibroblast cultures 
from French patients. These findings demonstrate the reproducibility of the AIP 
induction and of the methods used, and they particularly underline the 
importance of employing the present ultramicrotechniques for a successful AIP induction. 
It is likely that amniotic fluid cells behave like skin fibroblasts 
in this test; if this proves to be so, then the 
induction of alkaline phosphatase should provide a useful technique for the 
prenatal diagnosis of cystic fibrosis. 