Ribonuclease in different types of saliva from cystic fibrosis patients.

The flow rate, the activity of ribonuclease (RNAase) and the concentration of protein were determined in whole saliva and in parotid and submandibular saliva from patients with cystic fibrosis (CF) and from healthy controls, both before and after stimulation of the salivary secretion. Lower flow rates were found in all types of saliva from CF-patients than in control saliva. Increased activity of RNAase was found in CF saliva, both before and after stimulation of the secretion. The concentration of protein was also increased, but to a lesser degree. No correlation was found between either RNAase activity or protein concentration and severity of the disease or age of the children. It is therefore unlikely that these disturbances are secondary to progression of the disease. Considerable variations in RNAase activity and protein concentration were observed, especially within the CF group, and therefore despite the significant increase in these variables in CF their estimation is of limited diagnostic value.