Immunological dynamics of memory T cells in gram-negative septic shock patients: a prospective clinical study

Septic shock induced by Gram-negative bacilli can lead to severe immune dysfunction. The dysfunction and reprogramming of memory T cells are closely involved in the immunosuppressive state of septic shock. This study aimed to investigate the dynamic changes of memory T cells in such patients and their association with clinical outcomes.

This study is a prospective clinical research. Thirty-five patients with Gram-negative septic shock were enrolled and classified into survival and non-survival groups. Peripheral blood samples were obtained on admission, day 2 and day 7 after admission, and patients were stratified into survival and death groups based on 28-day survival status. Flow cytometry was performed to analyze the proportions of lymphocyte subsets as well as CD4⁺ and CD8⁺ memory T cell subsets, including naive, effector, central memory, and effector memory T cells. Intracellular cytokine staining was used to evaluate their functional capacity to IL-2, TNF-α, and IFN-γ.

Compared with survivors, non-survivors showed significantly reduced counts of CD8⁺ T cells, B cells, and NK cells. In memory T-cell subset analysis, non-survivors exhibited a significantly higher proportion of CD8⁺ T_CM cells at admission and a markedly lower proportion of CD8⁺ T_EM cells on day 7. Functionally, CD8⁺ T_CM cells from non-survivors showed enhanced IL-2 production, while CD8⁺ T_EM cells displayed diminished TNF-α and IFN-γ production on day 7. Further analysis revealed that the proportion and activation status of CD8⁺ T_CM cells at admission had good predictive value for 28-day mortality.

Patients with Gram-negative septic shock exhibited early elevation in the proportion and activity of CD8⁺ T_CM cells, and a decrease in the number and functional impairment of CD8⁺ T_EM cells in later stages. The dynamic changes in CD8⁺ memory T-cell subsets are associated with clinical outcomes, showing preliminary potential as candidate immune indicators for prognosis assessment, which needs further validation in larger cohorts.