Cytokines and periodontal disease: immunopathological role of interleukins for B cell responses in chronic inflamed gingival tissues

Abstract

Localized and chronically-inflamed gingival tissues of adult periodontitis (AP) are generally characterized as a hyper-responsiveness of B lineage cells where increased numbers of plasma cells occur. It was previously shown that high numbers of IgG subclass antibody-secreting cells (e.g., IgG1 > IgG2 > IgG3 > or = IgG4) with significant numbers of IgA subclass antibody-producing cells were seen in enzymatically dissociated gingival mononuclear cells (GMC) from inflamed periodontal tissues. An interesting finding was that the frequency of IgA2 plasma cells was elevated in the severe stage of AP when compared with the moderate stage. IgM plasma cells were essentially not found in these tissues. To understand the cytokine involvement in these increased B cell responses in inflamed gingiva, GMC isolated from inflamed tissues of AP patients were examined for cytokine production, specifically for IL-2, IL-4, IL-5, and IL-6 at both the protein and mRNA levels, since these cytokines have been shown to be essential interleukins for the regulation of the B cell response. Freshly-isolated GMC and peripheral blood mononuclear cells (PBMC) from AP patients were initially examined for IL-6 production because of its essential role for the terminal differentiation of B cells to become Ig-producing plasma cells. High levels of IL-6 were produced by GMC but not by PBMC unless cells were stimulated with T cell mitogen. A similar findings was also obtained when levels of IL-6 specific mRNA were examined in GMC and PBMC.(ABSTRACT TRUNCATED AT 250 WORDS)