CD39 identifies terminally exhausted CD8⁺ T cells in mice with chronic LCMV infection.

<p>(<b>A</b>) Expression of CD39 and CD44⁺ by mouse CD8⁺ T cells 30–35 days following LCMV Armstrong (left) or Clone 13 (right) infection. (<b>B</b>, <b>C</b>) Representative histograms (left) of CD127 (B) and PD-1 (C) expression by CD39^high and CD39^int CD8⁺ T cells from Clone 13 (red and blue, respectively) and CD39^int from Armstrong (filled gray) infected mice on d35 p.i. (left). Fraction of CD127⁺ (B) and MFI of PD-1 in PD-1⁺ cells (C) is shown on the right. Results are from 5 mice. (<b>D</b>) Fraction of CD39^high and CD39^int CD44⁺ CD8⁺ T cells expressing different combinations of co-inhibitory receptors PD-1, 2B4, and Lag3. (<b>E</b>) Average number of co-inhibitory receptors expressed by CD39^int (left) or CD39^high (right) CD8⁺ T cells at d35 p.i. following LCMV Clone 13 infection. (<b>F</b>) Representative plots of T-bet and Eomes expression in CD39^int (left) and CD39^high (right) cells as in (A). Summary of results is shown on the right. Data are representative of three experiments of 5 mice per group. Statistical significance was assessed with Student’s t-test (B, C, F) with Holm-Sidak multiple comparison correction (D). **<i>P</i> < 0.01, ****<i>P</i> < 0.0001.