Colloid and crystal formation in parotid saliva of cystic fibrosis patients and non-cystic fibrosis subjects. I. Physicochemistry.

Two types of turbidity were found in parotid saliva from both cystic 
fibrosis (CF) patients and non-CF subjects. On cooling saliva, a rapidly 
forming, reversible, cold-dependent turbidity appeared in increasing amounts with decreasing temperature 
and increasing protein concentration. At 37 degrees, a slowly forming, stable 
turbidity appeared in increased amounts in parotid saliva samples containing increased 
amounts of calcium. The 2 degree centrifuged pellet consisted predominantly of 
protein, whereas the 37 degree pellet contained calcium, inorganic phosphate, and 
protein. The cold- dependent turbidity at 2 degrees was not inhibited 
by EDTA, but 37 degrees turbidity was dramatically inhibited. Urea and 
guanidine hydrochloride reduced 2 degree turbidity, and, to a lesser extent, 
inhibited 37 degree turbidity. The tendency towards higher levels of protein, 
amylase, and calcium in CF compared with child control parotid saliva 
(4, 6) causes a greater incidence and degree of turbidity formation 
in saliva of CF patients. In this paper only the nature 
of the turbidity has been investigated, not its relative occurrence in 
each group of subjects. 