Human submandibular gland tissue in culture I. Sulphate incorporation and tissue culture technique.

In vitro cultivation of human submandibular gland tissue resulted in release of salivary proteins corresponding to about 50% of the total content after 48 hours. The admixture of plasma proteins as judged by single radial immunodiffusion took place early in the incubation period, and could be reduced by discarding the first washing medium. Hydroxyproline measurements in the medium indicated that the autolysis increased significantly after two days of incubation. Isoelectric focusing of human submandibular proteins resulted in fractions with isoelectric points closely resembling those demonstraded earlier for monkey submandibular gland proteins, but with larger acid fractions and smaller basic fractions. Virus haemagglutination inhibition (HAI) activity and sulphate incorporation was demonstrated in the most acidic, viscous fractions, whereas L-leucine incorporation was found in all fractions of the isoelectric scale. No sulphate affinity to submandibular proteins, independant of the in vitro protein synthesis, could be detected by equilibrium dialysis or other control measures.