Abstract: CD4+ T cell is a T cell with the immune activity, playing an important role in the immune modulation of human bodies. According to the different cytokines secreted by them, T helper cells can be divided into two subgroups named Thl and Th2, and they participate in the modulation of cell mediated and humoral immune response respectively. In a normal immune response, Th1/Th2 are in a dynamic balance. Periodontal destruction depends on the balance of Th1 and Th2 in the local periodontal environment. Any shift in the balance between a
protective T helper type 2-dominant response and a destructive T helper type 1-dominant response is a risk factor for periodontal disease initiation and progression.