Monoclonal antibody-mediated modulation of the humoral immune response against mucosally applied Streptococcus mutans

Systemic immunization with antigen coupled to monoclonal antibody. (MAb) ha s been used by several investigators to increase the number of Mab-producin g hybridomas against an antigen and to elicit antibodies specific far poorl y immunogenic epitopes. This strategy has implications far vaccine design i n that protective immunity is not necessarily: directed at immunodominant e pitopes of pathogens and may be improved by deliberately shifting the immun e response toward subdominant epitopes. To our knowledge, no studies to dat e have addressed the potential for immunomodulatory activity. mediated by M Abs bound to mucosally applied antigen. To test whether administration of a n exogenous MAb directed against a streptococcal surface protein could infl uence the humoral immune response, BALB/c mice were immunized orally by gas tric intubation or intranasally with Streptococcus mutans alone or S. mutan s complexed with a MAb directed against the major surface protein P1. Signi ficant changes in the subclass distribution, as web as the specificity, of anti-pi serum immunoglobulin G antibodies were demonstrated in groups of mi ce which received S. mutans coated with the anti-P1 MAb versus those which received S. mutans alone. Alterations in the humoral immune response were d ependent on the amount of anti-P1 MAb used to coat the bacteria. In additio n, differences in the anti-P1 immune responses were observed between groups of mice immunized via oral versus intranasal routes. In summary, an exogen ous MAb complexed with a streptococcal antigen prior to mucosal immunizatio n can influence the immunoglobulin isotype and specificity of the host humo ral immune response against the antigen.