Immunoglobulins and innate factors of immunity in saliva of children prone to respiratory infections.

Serum and salivary total IgA, IgG and IgM as well as salivary innate non-immunoglobulin antimicrobial factors (lysozyme, lactoferrin, salivary and leukocyte peroxidase systems) were measured in 13 children prone to recurrent respiratory infections and compared to their age-matched healthy controls. Serum IgG and IgM levels were significantly elevated and salivary IgA remarkably low in infection-prone children as compared to the controls. However, the levels of secretory piece-bearing IgA were about the same in both groups. There were no significant differences between the two groups in serum IgA levels or in any of the non-immunoglobulin factors. The results indicate that low salivary IgA is associated with recurrent respiratory infections.