Figure 4.

CD8⁺ T-cell subset composition and antigen-independent CD8⁺ T cell activation in the BM after CLP. Sepsis or sham surgery was induced in WT mice and BM cells were isolated 24 h later. The expression of CD69 on diverse CD8⁺ T-cell subsets was determined by flow cytometry. (A) Gating strategy of naïve (T_N), effector/effector memory (T_Eff/EM), central memory (T_CM), and virtual memory (T_VM) CD8⁺ T cells. Representative contour plots of one sham and one CLP mouse are shown. Numbers indicate the percentage of cells in the respective quadrant. (B) Cell count of CD8⁺ T-cell subsets from individual mice. (C) Expression of CD49d on BM CD8⁺ T_VM cells in comparison with splenic CD8⁺ T_Eff/EM cells as positive control. Numbers indicate the percentage of positive cells according to fluorescence minus one (FMO) indicated as gray line. (D) CD69 expression on CD8⁺ T cell subsets from individual mice. Horizontal lines indicate the median with interquartile range of n = 17–21 mice per group. (E) Histogram of CD69 expression of gated CD8⁺ T_VM from one representative sham and one CLP mouse. The dashed line indicates the threshold for positive staining according to the isotype control. (F) CD8⁺ T cells from DO11.10 mice were adoptively transferred into WT mice prior to CLP or sham surgery. Transferred ovalbumin-specific cells were identified as KJ1-26⁺ cells. The histogram depicts the expression of CD69 on gated KJ1-26⁺ T_VM cells from one representative sham and one CLP mouse. Statistically significant differences were tested using the Mann–Whitney U-test. *p < 0.05; ***p < 0.001.