Figure 5. Sts1 and Cbl-b contribute to the attenuated responsiveness of naive Nur77-GFP CD8⁺ T cells.

(A and E) Contour plots depict CD25 and CD69 upregulation in naive, polyclonal GFP^LO-like and GFP^HI-like CD8⁺ T cells stimulated for 24 hours with 0.25 μg/ml anti-CD3 and APCs. Numbers indicate the percentage of cells within each quadrant. Bar graphs depict the frequencies of CD25^HICD69^HI cells from three to four independent experiments. (B and F) Bar graphs show the ratio of %CD25^HICD69^HI Sts1^−/− cells (in B) or Cbl-b^−/− cells (in F) to %CD25^HICD69^HI WT cells, within GFP^LO-like (blue) and GFP^HI-like (red) populations. (C and G) Contour plots of IFNγ-secretion of CD8⁺ T cells stimulated as in A and E, after a 45-minute IFNγ-secretion assay. Numbers indicate the frequency of cells within the IFNγ⁺ gate. Bar graphs show the percentages of IFNγ⁺ cells from three to four independent experiments. (D and H) Bar graph shows the ratio of the frequencies of Sts1^−/− (in D) or Cbl-b^−/− (in H) versus WT IFNγ-secreting cells within the GFP^LO-like (blue) and GFP^HI-like (red) cell populations. Some of the WT data points for experiments in A, C, E, and G overlap since two experiments with Sts1^−/− and Cbl-b^−/− T cells were conducted simultaneously. Overlapping WT data points are labeled with squares instead of circles. Data represent three to four independent experiments with n = 3–4 mice. All bars depict the mean and error bars depict ± s.d. Statistical testing was performed by unpaired two-tailed Student’s t test in A, C, E (upper panel), F, and G (upper panel). Statistical testing was performed by unpaired two-tailed Student’s t test with Welch’s correction in B, D, E (lower panel), G (lower panel), and H. n.s., not significant.