Nonspecific induction of immunoglobulin M antibodies to periodontal disease-associated microorganisms after polyclonal human B-lymphocyte activation by Fusobacterium nucleatum.

The production of antibodies to oral bacteria was determined in lymphocyte cultures stimulated with sonicated Fusobacterium nucleatum, a potent inducer of polyclonal B-cell activation. After 9 days the cultures were examined by a microenzyme-linked immunosorbent assay for immunoglobulin M (IgM) antibodies to F. nucleatum, Bacteroides gingivalis, Actinomyces viscosus, and Streptococcus sanguis. Antibodies to these four bacteria were detected in cultures stimulated with polyclonal B-cell activation-inducing concentrations of F. nucleatum. However, significant concentrations of antibodies to F. nucleatum, but not to the other three microorganisms, were produced in cultures that received suboptimal polyclonal B-cell activation-inducing doses of F. nucleatum. Absorption studies indicated the specificity of the antibodies to each of the bacteria tested. IgM antibody production induced by F. nucleatum was enhanced by the addition of T cells. The production of IgM antibodies to the bacteria was reproducible in cultures from a single person tested on 3 consecutive days. The concentration of antibodies in replicate cultures, however, fluctuated greatly. To obtain consistent responses on successive days, multiple replicate cultures were required. These results suggest that F. nucleatum, which is frequently present in subgingival plaque, could induce the production of antibodies not only to F. nucleatum, but also to other microorganisms associated with periodontal diseases.