Passive immunisation with serum and immunoglobulins against dental caries in rhesus monkeys

Active immunisation with Streptococcus mutans induced protection against dental caries in rhesus monkeys, and this was associated with serum antibodies. Passive transfer of immune serum with IgG, IgM, and IgA antibodies to Strep. mutans failed to induce protection against dental caries. However, when separated IgG, IgM, and IgA sera were given, IgG induced significant protection but IgA or IgM antibodies to Strep. mutans did not. IgA and IgM may compete or interfere with the protective effect of IgG antibodies, and the ratio of IgG/IgA and IgG/IgM antibodies might be an important factor in immunisation against dental caries.