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• ·T cells in pleural effusion have higher levels of STAT3 phosphorylation. • ·Multifunctional T cells of APTB patients have higher pSTAT3 levels. • ·The STAT3+ pSTAT3- phenotype of Mtb-specific T cells tended to be more anti-apoptotic. Tuberculosis (TB) remains one of the most serious infectious diseases in the world. Our aim was to investigate the regulatory role of STAT3 and pSTAT3 in the regulation of T cell immunophenotype and cell function. Twenty-five active pulmonary tuberculosis (APTB) patients, 18 latent tuberculosis infection (LTBI) patients, and 20 healthy controls (HCs) enrolled in this study. T cell phenotype and expression of STAT3 and pSTAT3 were detected by flow cytometry. Compared with HCs, the expression of pSTAT3 in CD4+ T and CD8+ T cells in peripheral blood of APTB patients was increased, and the expression was higher in pleural effusion. Multifunctional T cells that simultaneously secrete IFN-γ, TNF-α and IL-17A have higher pSTAT3 expression levels. Mtb-specific T cells from APTB patients had a higher cell frequency of the STAT3+ pSTAT3+ phenotype and a reduced cell frequency of the STAT3+ pSTAT3- phenotype compared with LTBI patients. Mtb-specific T cells with STAT3+ pSTAT3+ phenotype had higher expression of PD-1 and PD-L1, while cells with STAT3+ pSTAT3- phenotype had higher expression of Bcl-2. STAT3 and pSTAT3 in T cells of APTB patients feature in the process of anti-apoptosis and cytokine secretion. At the same time, the higher pSTAT3 may be related to the degree of cell functional exhaustion. The pSTAT3 level of T cells is related to the infection status and may indicate the clinical activity of the disease, which provides a new idea for the clinical identification and treatment of active pulmonary tuberculosis. [ABSTRACT FROM AUTHOR]

• Cytotoxic cells decreased but activation increased in septic shock patients. • The function of toxic cells 2–3 days after admission indicated the clinical outcome. • Dynamic monitoring of cytotoxic cells in patients with septic shock was key. : Septic shock is a great threat to human life. Our aim is to explore the immune status and dynamic changes of circulating cytotoxic cells in septic shock patients. : Forty-eight septic shock patients (9 non-survivors and 39 survivors) and 30 healthy controls (HCs) were enroled in our study. The function of cytotoxic cells was dynamically monitored by flow cytometry. : The number of circulating CD8+ T and NK cells decreased significantly in septic shock patients, while the number of CD8+ T cells rose in survivors 5 days after admission. The frequency of HLA-DR+CD8+ T / NK cells increased in both groups after admission but decreased in non-survivors on day 3. Moreover, the frequency of GrA+/GrB+/perforin+NK and GrB+CD8+ T cells decreased to varying degrees in both groups, and the frequency of GrB+/perforin+CD8+ T cells on the second day of non-survivors was significantly lower than that of survival patients. Besides, the frequency of CXCR3+CD8+ T / NK cells was decreased in both groups and remained low in non-survivors, but remarkably increased in survivors after day 3. And the concentrations of cytokines IL-6, IL-10, TNF-α and IFN-γ were significantly increased in septic shock patients. : Circulating CD8+ T and NK cells reduced but activation function was compensatory enhanced in septic shock patients. The frequency of GrB+/PFP+CD8+ T and CXCR3+CD8+ T / NK cells may predict the progression of septic shock patients 2–3 days after admission. [ABSTRACT FROM AUTHOR]