Local and systemic immune response to orally administered liposome-associated soluble S. mutans cell wall antigens.

The aim of the present study was to develop an immunization procedure which preferentially stimulated the IgA system of rats, with release of IgA in secretions. Rats immunized by intragastric route with liposome-associated soluble antigen extracted from Streptococcus mutans cell wall, showed a significantly higher IgA (and IgG) response than did rats injected with the soluble antigen alone. In saliva, maximal antibody titres were obtained 11 days after the beginning of intubations for IgA, and 16 days for IgG. After a booster immunization, the secondary response occurred very quickly in saliva and, like the primary response, it was almost exclusively of the IgA class. This demonstrates, on one hand the existence of immunological memory in the IgA system and, on the other, the efficiency of liposomes as insoluble adjuvants in eliciting an immunological response.