In addition, the presence of type 1 cytokines in the gingival sulcus fluid of periodontitis patients has been proposed to be the main cause of Porphyromonas gingivalis-specific IgG2 production, while Porphyromonas gingivalis-dendritic cell-NK cell interaction can produce IFN-γ and type 1 cytokines in a short period of time (52). The gene discussed is IFNG; the disease is periodontitis.