Examination of parotid saliva for antibodies reacting with Streptococcus mutans, lipoteichoic acid and peptidoglycan by the enzyme-linked immunosorbent assay.

Human parotid saliva was investigated for the presence of IgA antibodies reacting with Streptococcus mutans, lipotechoic acid (LTA) and peptidoglycan. By using an enzyme-linked immunosorbent assay, ELISA, it was shown that the salivas of 12 subjects contained antibodies reacting with S. mutans serotype c and d and with LTA. Six salivas were tested against peptidoglycan but these tests indicated only low levels of antibodies. Absorption of saliva with whole cells of S. mutans inhibited the homologous reaction by up to 87% and the reaction with LTA by up to 52%. Also prior treatment of saliva with LTA caused a decrease in the salivary IgA reaction with LTA and with whole cells of S. mutans. Addition of peptidoglycan to saliva did not markedly affect the salivary IgA reaction with S. mutans. The data show that LTA may be responsible for part of the salivary IgA reaction with whole cells of S. mutans. The significance of LTA in this reaction may vary between different subjects and for different serotypes of S. mutans.