In addition, in patients with oral lesions due to HIV infection [121], median CD38 levels on the surface of T lymphocytes in peripheral blood were found to be significantly higher in patients with oral mucosal lesions than in patients without oral lesions, and median CD38 levels were also significantly higher in patients with gingivitis and periodontitis, suggesting that elevated CD38 expression levels in peripheral blood in HIV-positive patients are associated with oral lesions. Here, CD38 is linked to periodontitis.