Figure 1. Upregulation of CD80 is maintained in Ag-experienced T cells compared to naïve T cells after virus infection. C57BL/6 mice were intravenously infected with 2×10⁶ PFUs of LCMV Arm or CL13. The mice were sacrificed at the days indicated post-infection and the SPs were analyzed. (A) Expression of CD80 on naïve CD8⁺ and GP33 tetramer-positive CD8⁺ T cells after Arm or CL13 infection. (B) Representative data showing expression of CD80 on CD44^lo and CD44^hi population among CD4⁺ and CD8⁺ T cells after Arm or CL13 infection. (C) Frequency of CD80⁺ cells among CD44^hiCD4⁺ and CD44^hiCD8⁺ T cells after Arm or CL13 infection. (D) Representative data showing expression of CD80 on GP33 tetramer-positive cells among CD8⁺ T cells. (E) Frequency of CD80⁺ cells among GP33 tetramer-positive cells after Arm or CL13 infection. These data are representative of 3 independent experiments (n=4 mice per group). Results represent mean±SEM.