Quantitation of submandibular proteins resolved from normal individuals and children with cystic fibrosis.

Submandibular secretions collected from children with cystic fibrosis (CF) showed increased protein 
concentrations (milligrams/milliliter) and increased amylase specific activity (units/milligram of protein) relative 
to normals secretions. These differences between normal (N) and CF secretions 
were as follows: protein, 1.25 plus or minus 0.51 (N), 1.75 
plus or minus 0.35 (CF) (P < 0.02); and amylase, 58 
plus or minus 18 (N), 80 plus or minus 19 (CF) 
(P < 0.001). To determine the basis for elevated protein in 
CF saliva, several major proteins resolved by polyacrylamide disc gel electrophoresis 
were quantitated by densitometry. These included four phosphoproteins (PP), serum albumin, 
an acid phosphatase-containing fraction, amylase, and an unidentified protein referred to 
as PI-7.1. Together, these proteins comprise greater than 75% of the 
total protein in the secretion. Differences in individual protein concentrations (milligrams/milliliter) 
resolved from normal and CF secretions, respectively, were as follows: PP2, 
0.02 plus or minus 0.01, 0.03 plus or minus 0.02 (NS, 
not significant); PP3, 0.06 plus or minus 0.04, 0.05 plus or 
minus 0.03 (NS); acid phosphatase fraction, 0.06 plus or minus 0.04, 
0.12 plus or minus 0.07 (P < 0.05); amylase, 0.09 plus 
or minus 0.04, 0.27 plus or minus 0.16 (P < 0.01); 
and pI-7.1, 0.04 plus or minus 0.02, 0.13 plus or minus 
0.08 (P < 0.02). Amylase, the most significant contributor to the 
elevated protein, comprised 26% of the total protein of normal secretions 
and 38% of the total protein of CF secretions. Thus, our 
results do not support the concept of a generalized increase in 
all organic components in CF submandibular secretions but, rather, increases in 
specific proteins, namely amylase, component pI-7.1, and an acid phosphatase-containing fraction. 
