Microflora of the oral cavity forms a biofilm that induces response of immune system at the mucous membranes. Transition to periodontal lesion is provided by certain classes of resident mucosal immune cells and inflammatory/immune cells migrating to the periodont. In periodontal diseases, Th1, Th2, Th17, Treg are detected. T regulatory cells (Tregs) are proven to comprise the main anti-inflammatory cell population. Th17 cells and Treg cells play an important role in osteoclast differentiation. IL-17 secreted by Th17 cells affects osteoclastogenesis and may induce macrophages to enhance the local inflammatory response. In this regard, the aim of our work was to identify the local immune cells in oral cavity which are associated with severity of chronic generalized periodontitis. The oral cavity cells from 58 persons aged 38-65 years of both sexes in their mature age with a diagnosis of «chronic periodontitis» were examined by means of flow cytofluorometry. When determining levels of CD64+CD16+CD14- neutrophils in the patients with periodontitis of different severity, a statistically significant increase of this cell population was revealed upon development of this disease. In mild cases of periodontitis, a significant increase of relative CD64+CD16+CD14-  neutrophil contents was revealed (Me = 36.16%, p < 0.05) compared to the control group (Me = 7.7%, Q0.25 = 2.4%, Q0.75 = 12%). When assessing relative numbers of CD14+ monocytes in periodontitis of various severity, we revealed a significant increase in the number of these cells in severe cases. When studying levels of regulatory T lymphocytes (CD4+CD25+CD127low) in periodontitis of different severity, we revealed significantly decreased amounts of this cell population during development of the disease. In mild cases of periodontitis, a decreased level of CD4+CD25+CD127low cells (p < 0.05, Me = 1356 cells/ml) was revealed, as compared with control group (Me = 10666 cells/ml). Although the concentration of CD4+CD25+CD127low (Me = 4709 cells/ml) in the patients with moderate periodontitis was higher than the values in milder cases, the range of the main values was comparable and lower, than in control group. In severe periodontitis, a significantly decreased concentration of regulatory T lymphocytes was revealed (Me = 2637 cells/ml). These results confirm the anti-inflammatory regulatory function of Tregs. Understanding the osteo-immune mechanisms of bone remodeling control will help to understand the pathophysiology of accelerated bone loss observed in severe chronic periodontitis.

Periodontal bacterial bioflm causes an innate and adaptive immune response of the host mucosa, leading to inflammation and destruction of the tissues supporting the periodontal. The progression of periodontitis depends not only on bacteria, since an inadequate immune response to microorganisms can accelerate the development of periodontitis. However, the exact mechanisms of the development of immune reactions remain unclear. Recent studies emphasize the existence of a typical innate response of resident and extravasated immune cells.Objective. To investigate the quantitative composition of non-resident subpopulations of lymphocytes in salivary fluid and to study the mechanisms of interaction of the cellular link of the innate and adaptive immune system in chronic generalized periodontitis of varying severity.Materials and methods. 49 people aged 26–67 years of both sexes were examined with a diagnosis of chronic periodontitis. The comparison group consisted of 17 people aged 26–44 years with no periodontal diseases. The state of the cellular link of the adaptive and local immune system of the oral cavity was assessed by the following phenotypes: CD3–CD16+56+; CD3+CD16+56+; CD3+; CD3+HLA-DR+; CD19+, CD19+HLA-DR+; CD19+CD5+CD27–; CD19+CD5–СD 27–; CD19+СD5–CD27+.Results. The number of T-NK cells decreased with a mild degree of periodontitis and increased with a severe degree. Similarly, CD3+HLA-DR+ decreased with mild periodontitis [Me = 0.148 cells/µl] and increased with moderate [Me = 0.247 cells/µl] and severe [Me = 0.448 cells/µl]. The number of B-lymphocytes with the CD19+, CD19+CD5+, CD19+CD5–CD27+ phenotype decreased to single cells per microliter during the development of the disease.Conclusion. The imbalance of the immune system caused by pathogenic colonization of the periodontium, at different degrees of severity, is an important factor in the occurrence and development of periodontitis, in which various subsets of B cells of the adaptive immune system play a certain role, closely interacting with the cellular link of the innate mucosal immune system