Salivary Ribonuclease in Cystic Fibrosis and Control Subjects

Abstract

Alkaline acid- and thermo-stable RNase was assayed in whole mixed saliva from controls and from cystic fibrosis (CF) heterozygotes and homozygotes. There was a significant difference in salivary RNase activity between control adults (n = 99) and CF heterozygotes (n = 77) (12.6 .+-. 0.60 and 36.6 .+-. 2.2 U/l, mean .+-. SE, respectively; P < 0.001) and between control children (n = 1834) and CF patients (n = 60) (7.9 .+-. 0.15 and 47.0 .+-. 5.4 U/l, respectively; P < 0.001). A statistically significant difference in salivary RNase activity was also found between control children and control adults (P < 0.001) and between CF homozygotes and CF heterozygotes (P < 0.001). The protein concentration was significantly increased by .apprx. 50-60% in saliva both from CF heterozygotes and from CF homozygotes (P < 0.001 for both groups). In view of the great overlapping in values between the groups, these tests can only be of limited use for diagnostic purposes.