Variation in levels of immunoglobulins A, G and E in human saliva

These immunoglobulins were quantitated in 303 individuals belonging to 37 negroid and 26 caucasoid American families. Levels varied widely from individual to individual and frequency distributions were skewed toward the low levels. IgA was detected in all individuals except three children; two of whom were young and the third deficient in serum IgA. No salivary IgG was detected in 10 per cent of individuals, including both adults and children. IgA levels increased throughout life; IgG increased up to the teens and then leveled off; salivary IgE, like serum IgE, peaked before 10 years of age. Concentration of total salivary protein increased throughout life. Salivary immunoglobulin and protein concentrations were generally similar in negroids and caucasoids, only a difference in IgE levels was significant. The amount of all three classes of immunoglobulins was positively correlated with the corresponding class of serum immunoglobulins. Offspring-parent and sib-sib comparisons revealed that genetic factors contribute significantly to the variation in salivary immunoglobulins, but the heritability estimates were less uniform than those for serum immunoglobulins.