The box plots depict the minimum and maximum values (whiskers), the upper and lower quartiles, and the median. resulted Rabbit polyclonal to GNRH in decreased mortality during sepsis. Mechanistically, this decreased mortality was associated with reduced caspase-3/7+ apoptotic T cells in 2B4C/C relative to WT, septic hosts. These results were corroborated by analysis of PBMCs isolated from human patients with sepsis, which showed increased frequencies of caspase-3/7+ apoptotic cells among 2B4+ relative to 2B4C T cells. Thus, 2B4 plays a critical role in sepsis-induced apoptosis in both murine memory T cells and those isolated from human patients with sepsis. bacterial infection followed by an lymphocytic choriomeningitis virus (LCMV) viral infection as described in Methods to generate an effector T cell response that would resolve and generate memory T cells (Figure 1A). We assessed the magnitude and kinetics of the CD4+ and CD8+ T cell responses during the expansion and contraction of the immune response following these infections. The frequency of CD44hi cells among both CD4+ and CD8+ T cell populations significantly increased on day 10 after infection and then significantly decreased by day 25 after infection (Figure 1, BCD). Mice were then infected with LCMV, and 10 days later the frequency of CD44hi cells among both CD4+ and CD8+ T cell populations significantly increased again (day 40, Figure 1, BCD) and then decreased on day 55 after infection (day 25 after LCMV infection). In sum, results indicate that our model resulted in the generation of animals that possess a significantly increased frequency of CD44hi memory T cells in both the CD4+ and CD8+ T cell compartments (CD4: 38.4% 1.3% versus 20.1% 1.5%, < 0.0001; CD8: 54.6% 1.5% versus 18.1% 1.4%, < 0.0001) (Figure 1, E and F). As shown in Supplemental Figure 1 (supplemental material available online with this KPT-6566 article; https://doi.org/10.1172/jci.insight.126030DS1), the increase in memory T cells shown in Figure 1, E and F, was due almost entirely to an increase in CD44hiCD62Llo effector memory cells (Tem) in both the CD4+ and CD8+ T cell compartments. Open in a separate window Figure 1 Generation and characterization of polyclonal memory T cells following infection.Naive B6 mice were infected with and allowed to develop a population of memory T cells. Mice were infected with LCMV 30 days later. Establishment of memory was assessed by flow cytometry 25 days after LCMV infection. (A) Schematic of experimental design. (B and C) Representative flow plots depicting CD44 expression on splenic CD4+ T cells following infection. (D) Expansion of CD44+ T cells in the spleen over time following antigenic challenge (= 20/group). (E and F) Summary of frequency of CD44hi cells among CD4+ and CD8+ T cell compartments in memory mice on day 55 following infection (per schematic in A) in the blood, KPT-6566 compared with the frequency of CD44hi cells in the blood of naive uninfected animals. Groups (= 5) were compared with the Mann-Whitney nonparametric test. ****< 0.0001. All data expressed as mean SEM. Memory mice exhibit significantly increased T cell loss during sepsis compared with naive hosts. Memory mice, as well as age- and housing-matched naive controls, were then subjected to CLP. Animals were sacrificed at 24 hours after CLP to assess the impact of sepsis on the magnitude of the T cell compartment. We found that antigen-experienced memory mice exhibited a statistically KPT-6566 significant increase in loss of CD8+ (but not CD4+) T cells following sepsis compared with naive septic animals (2.68 106 1.85 105 versus 5.28 106 3.01 105, < 0.0001) (Figure 2, A and B). Based KPT-6566 on the results that CLP led to a greater loss KPT-6566 of CD8+ T cells in memory mice compared with naive septic control animals, we hypothesized that memory mice would exhibit increased mortality during sepsis. However, analysis of 7-day survival revealed no statistically significant difference between naive and memory mice after CLP (Figure 2C). Open in a separate window Figure 2 Memory mice exhibit significantly increased T cell loss during sepsis compared with naive hosts.(A and B) Summary quantification of total number of.