CD4+ T-lymphocytes can be divided into helper T cells(Th 1, 2, and 17) when stimulated with external factors, such as bacteria or viruses. Th1 cells mainly secrete interferon(IFN)-γ, interleukin(IL)-2, and tumor necrosis factor(TNF)-β, which may result in inflammation and tissue destruction. Th2 cells mainly secrete IL-4, 5, 6, and 10, which are negative regulators or protection factors in inflammation sites. Th17 cells express IL-23 receptor and secrete IL-6, IL-17, and transforming growth factor-β, which are important pre-inflammatory cytokines. Th1 cells can aggravate The degree of periodontal tissue inflammation and alveolar bone destruction. Th2 cells can also protect periodontal tissues and reduce lesion severity. In addition, Th17 cells play an important role in chronic periodontitis inflammation and bone destruction. Th2 cells confer protection by controlling the production and biological effect of These cytokines and can block abnormal immune processes; hence, Th2 cells can be used in clinical assessment and control of chronic inflammation of periodontitis. Research in this direction may provide Theoretical basis for treatment of periodontitis with different cytokines.
