Regulatory T (Treg) cells limit the onset of effective antitumor immunity, through yet-ill-defined mechanisms. We showed the rejection of established ovalbumin (OVA)-expressing MCA101 tumors required both the adoptive transfer of OVA-specific CD8(+) T cell receptor transgenic T cells (OTI) and the neutralization of Foxp3(+) T cells. In tumor-draining lymph nodes, Foxp3(+) T cell neutralization induced a marked arrest in the migration of OTI T cells, increased numbers of dendritic cells (DCs), and enhanced OTI T cell priming. Using an in vitro cytotoxic assay and two-photon live microscopy after adoptive transfer of DCs, we demonstrated that Foxp3(+) T cells induced the death of DCs in tumor-draining lymph nodes, but not in the absence of tumor. DC death correlated with Foxp3(+) T cell-DC contacts, and it was tumor-antigen and perforin dependent. We conclude that Foxp3(+) T cell-dependent DC death in tumor-draining lymph nodes limits the onset of CD8(+) T cell responses.

Background: Acute exacerbation is a substantial cause of death in patients with idiopathic pulmonary fibrosis with poorly described prognostic factors. Objectives: To review the features associated with acute exacerbation of idiopathic pulmonary fibrosis and assess its prognostic factors. Methods: Thirty-seven occurrences of acute exacerbation of idiopathic pulmonary fibrosis were retrospectively reviewed in the medical records of 27 patients. Clinical presentation, radiographic studies, pulmonary function tests, laboratory data, treatment, and outcome were analyzed. Results: Acute exacerbation of idiopathic pulmonary fibrosis occurred more frequently between December and May (75.7%) than between June and November (24.3%) (p = 0.01). In-hospital mortality was 27% and median survival was 4.2 months (range 0.2–36.6). Significant differences between nonsurvivors and survivors included the time elapsed between their admission and the initiation of treatment for acute exacerbation (6 vs. 3.1 days, p = 0.04), lactate dehydrogenase levels at admission (801 vs. 544.6 IU/l, p = 0.002), impairment of the prior forced vital capacity (51.2 vs. 65%, p = 0.01) and diffusing capacity for carbon monoxide (21.7 vs. 34%, p = 0.01). Furthermore, the evolution of gas exchange in the first 10 days after the initiation of treatment was associated with in-hospital and long-term mortality. Conclusions: Acute exacerbations of idiopathic pulmonary fibrosis are more frequent during winter and spring. The time between admission and initiation of treatment is a new reported prognostic factor that should be investigated further. This finding highlights the need for a fast diagnostic approach that should probably be standardized. Early gas exchange modifications reflect the response to treatment and predict the prognosis.

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