Intrafamilial similarity in immunoblot profiles of salivary immunoglobulin A antibody activity to oral streptococci

Analysis of the salivary immunoglobulin A (IgA) antibody activity to antigens separated from oral streptococci was carried out on 49 individuals in 11 families. The aim of this study were to i) study the human salivary IgA activity within families to antigens separated from reference strains of Streptococcus mutans, Streptococcus sobrinus and Streptococcus parasanguis and ii) to search for potential differences in the salivary IgA activity to the streptococcal antigens several years apart. The immunoblot revealed similarity in saliva IgA response within the families. A majority of the bands, ～7 (median) for each extract was found in both child and parent. A few bands (～3) were found in parents but not in children. Only one to two bands were found in children's saliva without a corresponding band in any of the parents. The antibody activity of saliva samples obtained several years apart was essentially unchanged, especially considering the total number of bands. Differences in the relative intensity of the bands could be seen, and a few bands appeared only in some immunoblots for a specific subject. For 3 of 4 children participating in the longitudinal study, more bands against mutans streptococci appeared with age.