Fig. 1

Programmed cell death protein 1 (PD-1) and signal-regulatory protein alpha (SIRPα) expression on CD8⁺ T cells during acute and chronic infection. Wild-type C57/BL6 mice were adoptively transferred with 1000 T cell receptor transgenic lymphocytic choriomeningitis virus (LCMV)-specific CD8⁺ T cells from the spleens of naive P14 mice and then infected with either LCMV Arm or Cl13. The cells were then analyzed at multiple time points by microarray and the data were made publicly available¹⁹. SIRPα (a) and PD-1 (b) expression were analyzed by Dunnett’s multiple comparisons test with each time point compared to time zero (n = 4 mice per time point except for d6 LCMV Arm, n = 3. SEMs are shown as bars). Representative flow cytometric contour plots of Thy1.1-gated, adoptively transferred P14 CD8⁺ T cells at 42 days postinfection with Arm (c) or CL13 (d) are shown. Numbers in the upper right quadrant are mean percentages of SIRPα+ cells (n = 4 Arm, n = 3 Cl13), P = 0.0029 by unpaired, two-way t test. Average mean fluorescence intensity of SIRPα expression (P = 0.0088 by unpaired two-way t test) (e). CD8⁺ splenocytes from naive (f), 7 dpi (g), 14 dpi (h), or chronic (i) Friend virus (FV)-infected mice were analyzed by flow cytometry for CD11a expression and FV-D^b gagL dextramer staining. A representative flow cytometry plot is shown. Dextramer⁺ CD11a⁺ (j, k) and dextramer⁻CD11a⁻ subsets (l–o) were further analyzed for PD-1 and SIRPα expression during the course of FV infection. Arrows originate in the quadrant further analyzed and point to the analysis. The percentage in each quadrant depicts the means from eight mice at each time point, with standard deviations in parentheses. The flow cytometric gating strategy is shown in supplementary Fig. 6a–d. Not significant (ns), p > 0.05, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, ****p ≤ 0.0001 (unpaired, two-way t tests)