OBJECTIVE: To evaluate the lymphocyte subpopulations and the levels of (1, 3)-β-d-glucan (BDG) and galactomannan (GAL) in sepsis patients with secondary invasive fungal infections (IFIs), and to investigate the association between lymphocytes and IFIs. METHODS: A retrospective case-control study of 47 patients with sepsis complicated by IFIs, 50 sepsis patients, and 50 healthy controls was conducted. The correlation between lymphocyte subsets and BDG, GAL levels was analyzed using the Spearman correlation method, and the diagnostic efficacy of IFIs-related factors was assessed using the receiver operating characteristic curve (ROC) analysis. RESULTS: The IFIs group exhibited significantly lower absolute lymphocyte counts (P <
0.05). The study revealed that both BDG and GAL levels were inversely correlated with the counts of total lymphocytes and CD4+ lymphocytes (BDG: R CONCLUSIONS: The reduced absolute counts of lymphocyte subsets in patients with IFIs complicated by sepsis suggest a state of immunosuppression. The concurrent assessment of BDG, GAL, total lymphocyte count, and CD4 T lymphocyte count demonstrates high diagnostic efficacy for identifying IFIs complicated by sepsis.