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

Theproduction ofantibodies tooral bacteria wasdetermined inlymphocyte cultures stimulated withsonicated Fusobacterium nucleatum, apotent inducer of polyclonal B-cell activation. After 9daysthecultures wereexamined byamicroenzyme-linked immunosorbent assay forimmunoglobulin M (IgM) antibodies to F.nucleatum, Bacteroides gingivalis, Actinomyces viscosus, andStreptococcus sanguis. Antibodies tothese fourbacteria weredetected incultures stimulated withpolyclonal B-cell activation-inducing concentrations ofF.nucleatum. However, significant concentrations ofantibodies toF.nucleatum, butnottotheother threemicroorganisms, wereproduced incultures thatreceived suboptimal polyclonal B-cell activation-inducing doses ofF.nucleatum. Absorption studies indicated thespecificity oftheantibodies toeachofthebacteria tested. IgM antibody production induced byF.nucleatum wasenhanced bytheaddition ofT cells. Theproduction ofIgMantibodies tothebacteria wasreproducible in cultures fromasingle person tested on3consecutive days. Theconcentration of antibodies inreplicate cultures, however, fluctuated greatly. Toobtain consistent responses onsuccessive days, multiple replicate cultures wererequired. These results suggest thatF.nucleatum, whichisfrequently present insubgingival plaque, could induce theproduction ofantibodies notonlytoF.nucleatum, but also toother microorganisms associated withperiodontal diseases. Chronic periodontitis ishistologically characterized byasubstantial accumulation ofantibody-secreting plasma cells (16, 25), anditis speculated thatmicroorganisms associated with this disease mayplay arole inactivating these B lymphocytes (Bcells) (5). Several recent studies havedemonstrated that microorganisms isolated fromchronic periodontitis lesions non-specifically stimulate multiple clones ofhumanBcells invitro (1,17,18,26).Suchstimulation is referred toaspolyclonal B-cell activation (PBA). Invitro PBA istypically measured by theproduction ofrelatively large amountsof immunoglobulin oranincrease inthenumberof hemolytic immunoglobulin-secreting cells (8).