Saliva can explain children’s weak immune defense, Swedish research shows

The saliva in the oral cavity is produced by large and small saliva glands. Small saliva glands are thought to account for some ten percent of the secretion. They are found everywhere in the oral cavity's mucous linings, such as the tongue, lips, gums, and cheeks. The glands continuously produce a secretion that on the one hand lubricates the mucous linings and on the other hand contains antimicrobial substances, which are part of both the specific and unspecific immune defense. The secretion protects us against infections and keeps the oral cavity moist.

Mikael Sonesson, a specialist in orthodontics and teacher at the Faculty of Dentistry, Malmö University, has studied whether the occurrence of specific and unspecific defense components in saliva differs with age. The study material examined consists of saliva collected with filter paper from various mucous lining areas in about 200 subjects. The subjects belong to three groups: preschool children, adolescents, and young adults.

"The main objective was to study the saliva flow and the occurrence of defense components in saliva from small saliva glands during the growth years. This has never been done before," says Mikael Sonesson.

The results show for instance that children have a smaller amount of the specific substance immunoglobulin A (IgA) compared with adults. The amount of some components belonging to the unspecific defense was similar, however.

The differences can be explained by the fact that the immune defense is not fully developed in small children. This development takes place at the age of ten to twelve years, although parts of the unspecific immune defense seem to be mature even in preschool children. Mikael Sonesson stresses that this explanation is thus far based only on the results of these preliminary studies.

Mikael Sonesson's studies mark the beginning of a mapping of defense components in healthy children. In cases of general diseases that require treatment with immunosuppressive drugs or radiation of the head/throat, the situation may be different. In such cases the immunological function of the defense components is probably crucial to the development of diseases in soft and hard tissues.

"There the differences may be of importance, and this is one of the things it would be interesting to study further."

The studies also reveal differences in growth between specific and unspecific defense components.

"It seems to take longer for the specific defense both in whole saliva and small-gland saliva to reach the adult level," says Mikael Sonesson, who plans new studies to examine the saliva of children undergoing orthodontic treatment.

"But more studies are required before we can say with certainty what importance these differences have."