Background: The aim of the study was to evaluate the role of high-mobility group box 1 (HMGB1)-phosphatase and tensin homolog deleted on chromosome ten (PTEN) signaling in T lymphocytes and monocytes upon sepsis. Methods: Thirty C57BL/6 male mice aged 8 -10 weeks old were randomly divided into sham, model, and inhibitor groups (n = 10). The model of sepsis was established through cecal ligation and perforation. Sham group was only subjected to cecum exposure, and then the wound was sutured without cecal ligation. After the operation, the inhibitor group was intraperitoneally injected with HMGB1-specific inhibitor glycyrrhizic acid (dose: 10 mg/kg) every 6 hours for 4 consecutive times, while sham and model groups were intraperitoneally injected with an equal dose of normal saline. The histopathological changes, cell apoptosis in spleen and thymus tissues, proliferative activity and apoptosis of T lymphocytes, chemotactic activity of monocytes, expression levels of tumor necrosis factor-alpha (TNF-??), interleukin-6 (IL-6) and IL-10, and expressions of HMGB1 and PTEN in mice were detected using hematoxylin-eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining, MTT assay, flow cytometry, transwell chemotaxis assay, enzyme-linked immunosorbent assay, and western blotting, respectively. Results: The cell apoptosis rate in spleen and thymus tissues, proliferative activity and apoptosis rate of T lymphocytes, chemotactic activity of monocytes, protein expressions of TNF-??, IL-6 and IL-10, and expressions of HMGB1 and PTEN significantly increased in the model group compared with those in the sham group (p < 0.05). However, the cell apoptosis rate in spleen and thymus tissues, T lymphocyte apoptosis rate, protein expressions of TNF-?? and IL-6, and expressions of HMGB1 and PTEN were significantly lower, while the proliferative activity of T lymphocytes, chemotactic activity of monocytes and protein expression of IL-10 were significantly higher in the inhibitor group than those in the model group (p < 0.05). Conclusions: Repressing HMGB1-PTEN signaling can effectively reduce the apoptosis rate of T cells, increase the proliferative activity of T cells, and enhance the function of monocytes in the case of sepsis. (Clin. Lab. 2022;68:xx-xx. DOI: 10.7754/Clin.Lab.2021.211024)