Elevated infiltration of Programmed cell death protein-1 high (PD-1^hi) interferon-gamma positive (IFN-γ+) forkhead box P3 positive (FOXP3+) T cells has been observed in chronic inflammatory conditions such as periodontitis and in HIV-infected tissues, reflecting a state of immune exhaustion and regulatory dysfunction. The gene discussed is IFNG; the disease is periodontitis.