Negative Regulation of Type I IFN Expression by OASL1 Permits Chronic Viral Infection and CD8+ T-Cell Exhaustion
Figure 4
Better responses of virus-specific CD8+ T cells and their prolonged survival in Oasl1 KO mice due to virus-specific T-cell-extrinsic factors.
GP33-specific TCR transgenic CD8+ T cells, P14 cells, were obtained from naïve P14 Thy1.1 congenic mice. 5×103 of P14 Thy1.1+ CD8+ T cells were adoptively transferred into WT and Oasl1 KO mice. The next day, both recipient mice were infected with LCMV CL-13 and splenocytes were isolated from the mice at 5 d p.i. (A) Massive expansion of virus-specific donor CD8+ T cells in the KO mice. Numbers in the representative plot (left) indicate the frequency of donor P14 Thy1.1+ CD8+ T cells among splenocytes while the absolute numbers of donor P14 Thy1.1+ CD8+ T cells present per recipient spleen are summarized in the graph (right). (B) Cytokine production from donor P14 Thy1.1+ CD8+ T cells after in vitro restimulation with GP33 peptide. Representative plots (left) are shown for co-expression of IFN-γ and TNF-α or IFN-γ and IL-2 on donor P14 Thy1.1+ CD8+ T cells; summarized graph (right) for the frequency of TNF-α- or IL-2-producing cells among IFN-γ+ CD8+ T cells. (C) Proliferative capability measurement on donor P14 Thy1.1+ CD8+ T cells by direct ex vivo staining. Representative Ki67 expression levels (MFIs, left) and summarized levels (right) on donor P14 Thy1.1+ CD8+ T cells are shown. Shade histogram indicates Ki67 expression level on P14 Thy1.1+ CD8+ T cells before adoptive transfer (a.t.); black line and red line histograms indicate Ki67 expression levels on P14 Thy1.1+ CD8+ T cells at 5 d p.i. after a.t. into WT and KO mice, respectively. (D) Cell death susceptibility of donor P14 Thy1.1+ CD8+ T cells. Representative (left) and summary (right) data after direct ex vivo staining of splenocytes for Annexin V (AV) and 7AAD. Donor P14 Thy1.1+ CD8+ T cells were analyzed. Data are given as mean + SD. Data are representative of two independent experiments (n = 4 per group in each experiment). ns, not significant; **, P<0.01; ***, P<0.001.