Salivary immunoglobulin A (IgA) is one characteristic humoral factor of the local immune system in the upper respiratory tract. Epidemiological studies emphasize the importance of secretory IgA in the protection from infections of the upper respiratory tract. However, due to high interindividual variability of secretion of salivary IgA, it remains difficult to define normal ranges. This series of studies focused on identification of factors influencing basal secretion of salivary IgA. The results indicate a significant relationship between age and salivary IgA concentration. Children below 7 years have lower salivary IgA concentration than children above 7 years or adults. Furthermore, a significant inverse relationship between saliva flow and salivary IgA concentration was found. Gender, mood states, salivary albumin, salivary catecholamines, and salivary cortisol were not associated with salivary IgA. It can be concluded that for defining normal ranges of salivary IgA, age and saliva flow have to be considered.
