5A–C). Furthermore, the frequency of CD4+ CD25+ regulatory T cells was unaltered (Fig. 5D). Neither did we detect any differences in steady-state frequencies of DC (CD11c+ cells), macrophages (F4/80+ cells), and granulocytes (Gr1+ cells) (data not shown). Finally,
EX 527 supplier we analyzed the activation state of CD4+ and CD8+ cells by staining CD62L and CD44, but did not detect any differences in the naïve and memory compartments of WT and vavFLIPR animals (Fig. 5E). We conclude that c-FLIPR does not affect immune cell populations in the steady state. Since c-FLIPS iscrucial during the early phase of an immune response in humans [11], we challenged vavFLIPR mice with L. monocytogenes, an obligate intracellular gram-positive bacterium. We chose L. monocytogenes since these bacteria are known to cause massive apoptosis of T cells [24, 25]. Therefore, we analyzed the frequencies of CD4+ and CD8+ T cells in the spleen via flow cytometry at day 3 postinfection with L. monocytogenes. Although infection reduced the frequencies of CD4+ and CD8+ T cells in both WT and vavFLIPR mice compared to uninfected control mice, a higher frequency of T cells
was observed in the transgenic mice (Fig. 6A and B). Consequently, we analyzed T-cell apoptosis by Annexin V staining. Surprisingly, we detected no differences in apoptosis levels in Panobinostat cell line the CD4+ T-cell compartment between infected WT, vavFLIPR, and uninfected control mice (Fig. 6C). In contrast, apoptosis of CD8+ T cells was increased in infected compared with uninfected WT mice (Fig. 6D). Most importantly, less apoptosis of CD8+ T cells was detected in vavFLIPR mice compared to WT mice (Fig. 6D). To further analyze the kinetics of cell death induced by Listeria, mice were infected with L. monocytogenes and T-cell apoptosis was determined on days 1, 3, and 5 postinfection. As before, apoptosis of CD4+ T cells was low and similar in both genotypes (Fig. 6E). ID-8 In agreement with the data described (Fig. 6D), less apoptosis
was detected in CD8+ T cells from vavFLIPR mice compared to CD8+ cells from WT littermates at days 1 and 3 (Fig. 6F). At day 5 apoptosis rates increased and no differences were detected between WT and vavFLIPR mice, suggesting that this effect was independent of death receptors. During a L. monocytogenes infection, bacteria accumulate in spleen and liver leading to inflammation and tissue destruction [24]. Therefore, we analyzed liver and spleen sections by histology. Five days after L. monocytogenes infection, we observed smaller and less numerous liver necrotic foci in vavFLIPR mice (Fig. 7A and B). In general, no differences in terms of character of the lesions were detected between transgenic and nontransgenic mice.