Cystic fibrosis: protease activity in saliva evaluated with chromogenic substrates.

The protease activities in saliva from individuals with cystic fibrosis (CF) were studied using four different chromogenic substrates. In the CF-group a significantly decreased protease activity in the range 50-70% was found, compared to an age- and sex-matched control group, but with considerable overlap between the CF-patients and the control patients. The trypsin-like activity found in CF-patients without chronic colonisation with Pseudomonas aeruginosa was significantly decreased and without overlap compared to the control patients. The results indicate that determination of salivary protease activity using chromogenic substrates may give additional information in patients with suspected cystic fibrosis, and indicate the possibility of an additional diagnostic test.