The gingival immune response to Actinobacillus actinomycetemcomitans in juvenile periodontitis

The established and advanced lesions of juvenile periodontitis-localized form (JP) are predominated by B-lymphocytes and plasma cells. Local immune processes may participate in protective or immunopathologic roles in the pathogenesis of this disease. Actinobacillus actinomycetemcomitans (A.a.) is implicated as a primary etiologic agent in JP. An in vitro gingival explant culture system was utilized to study the specificity of immunoglobulins produced by diseased JP tissues. A dot-immunobinding assay demonstrated that 46% of the supernatant fluids (SF) from explant cultures of diseased tissues (n = 39) were positive for the presence of antibody to A.a. Y4, while 61% of autologous JP sera (n = 39) tested positive. For rapidly progressive (RP) and adult periodontitis (AP) SF, 50% and 40% were positive for A.a. Y4, respectively. Seventeen percent of SF from healthy tissue were positive for A.a. Y4. There was no significant difference between JP SF reactivities to A.a. Y4 when compared to reactivities of SF from AP and RP patients. Only 10% of JP SF were positive for Porphyromonas asaccharolytica, a non-oral control microorganism. The de novo biosynthesis of antibody in JP tissue, reactive with A.a. Y4, was demonstrated with Staph Protein A isolated 14C-labeled IgG (SPAG) and the use of a dot-immunobinding assay and autoradiography. The in vitro gingival tissue explant culture system described provides a useful model for the study of the synthesis and specificity of localized immunoglobulins produced by diseased tissues of JP patients.