Salivary IgA in minor-gland saliva of children, adolescents, and young adults

According to previous studies, minor glands produce about 35% of the total salivary immunoglobulin A (salivary IgA). The age-dependent increase in whole-saliva salivary IgA concentrations has been studied extensively, but we found no published reports comparing the minor-gland saliva concentrations of salivary IgA in children, adolescents, and adults. In this study we measured the concentration of salivary IgA in saliva from the labial and the buccal minor glands of children, adolescents, and adults. Three age groups donated saliva for analysis: 3-yr-old children, 14-yr-old adolescents, and 20- to 25-yr-old adults. Minor-gland saliva was collected on filter paper and unstimulated whole saliva was collected by draining into a tube, and the salivary IgA concentration was determined by ELISA. The salivary IgA concentration in labial saliva was significantly lower among 3-yr-old children (0.037 mg 100 ml(-1), SD = 0.035) than among 14-yr-old adolescents (0.126 mg 100 ml(-1), SD = 0.128) and adults (0.128 mg 100 ml(-1), SD = 0.13). The 3-yr-old children also had significantly lower whole-saliva salivary IgA values compared with the other age groups (0.09 mg 100 ml(-1), SD = 0.091; 0.179 mg 100 ml(-1), SD = 0.149; and 0.170 mg 100 ml(-1), SD = 0.099, respectively). This increase in salivary IgA concentrations with age might reflect a developing immune response in the growing child.