In this report we have investigated the role of the Ets-1 transcription factor in the differentiation of the NK cell lineage in mice. Splenic NK cells express high levels of Ets-1. Ets-1-deficient mice produced by gene targeting developed mature erythrocytes, monocytes, neutrophils, and T and B lymphocytes. However, spleens from the Ets-1-deficient mice contained significantly reduced numbers of natural killer (NK) cells, and splenocytes from these mice lacked detectable cytolytic activity against NK cell targets in vitro. Moreover, unlike wild-type animals, Ets-1-deficient mice developed tumors following subcutaneous injection of NK-susceptible RMA-S cells. These NK cell defects could not be correlated with defects in the expression of IL-12, IL-15, and IL-18 or the IL-2 or IL-15 receptors. Thus, Ets-1 defines a novel transcriptional pathway that is required for the development of the NK cell lineage in mice.

The basic/leucine zipper (bZip) transcription factor, CREB, binds to the CRE element (TGANNTCA). The transcriptional activity of CREB requires phosphorylation of the protein on a serine residue at position 119 (ref. 6). CREs are present in a number of T-cell genes but the precise role of CREB in T-cell differentiation and function was unknown. Here we show that resting thymocytes contain predominantly unphosphorylated (inactive) CREB, which is rapidly activated by phosphorylation on Ser 119 following thymocyte activation. T-cell development is normal in transgenic mice that express a dominant-negative form of CREB (CREBA119, with alanine at position 119) under the control of the T-cell-specific CD2 promoter/enhancer. In contrast, thymocytes and T cells from these animals display a profound proliferative defect characterized by markedly decreased interleukin-2 production, G1 cell-cycle arrest and subsequent apoptotic death in response to a number of different activation signals. This proliferative defect is associated with the markedly reduced induction of c-jun, c-fos, Fra-2 and FosB following activation of the CREBA119 transgenic thymocytes. We propose that T-cell activation leads to the phosphorylation and activation of CREB, which in turn is required for normal induction of the transcription factor AP1 and subsequent interleukin-2 production and cell-cycle progression.

Prior murine and human studies suggest that vascular endothelial growth factor (VEGF) contributes to endothelial cell activation and severity of illness in sepsis. Furthermore, circulating levels of soluble VEGF receptor 1 (sFLT) levels were found to increase as part of the early response to sepsis in mice. The objective of the study was to evaluate the blood levels of free VEGF-A and sFLT in patients presenting to the emergency department (ED) with suspected infection and to assess the relationship of these levels with severity of illness and inflammation. It was a prospective, observational study initiated in the ED of an urban, tertiary care, university hospital. Inclusion criteria were (1) ED patients aged 18 years or older and (2) clinical suspicion of infection. Eighty-three patients were enrolled in the study. The major findings were that (1) the mean VEGF and sFLT levels were increasingly higher across the following groups: noninfected control patients, infected patients without shock, and septic shock patients; (2) initial and 24-h VEGF levels had a significant correlation with the presence of septic shock at 24 h; (3) initial and 24-h sFLT levels correlated with Acute Physiology Age Chronic Health Evaluation II and Sepsis-related Organ/Failure Assessment scores initially and at 24 h; and (4) VEGF and sFLT levels correlated with inflammatory cascade activation. This is the first report of sFLT as a potential new marker of severity in patients with sepsis. Vascular endothelial cell growth factor and its signaling axis are important in the endothelial cell response to sepsis, and further elucidation of these mechanisms may lead to advances in future diagnostic and therapeutic opportunities.

Syncope is a common presentation to the Emergency Department (ED); however, appropriate management and indications for hospitalization remain an ongoing challenge. The objective of this study was to determine if a predefined decision rule could accurately identify patients with syncope likely to have an adverse outcome or critical intervention. A prospective, observational, cohort study was conducted of consecutive ED patients aged 18 years or older presenting with syncope. A clinical decision rule was developed a priori to identify patients at risk if they met any of the following 8 criteria: 1) Signs and symptoms of acute coronary syndrome; 2) Signs of conduction disease; 3) Worrisome cardiac history; 4) Valvular heart disease by history or physical examination; 5) Family history of sudden death; 6) Persistent abnormal vital signs in the ED; 7) Volume depletion; 8) Primary central nervous system event. The primary outcome was either a critical intervention or an adverse outcome within 30 days. Among 362 patients enrolled with syncope, 293 (81%) patients completed their 30-day follow-up. Of these, 201 (69%) were admitted. There were 68 patients (23%) who had either a critical intervention or adverse outcome. The rule identified 66/68 patients who met the outcome for a sensitivity of 97% (95% confidence interval 93-100%) and specificity of 62% (56-69%). This pathway may be useful in identifying patients with syncope who are likely to have adverse outcome or critical interventions. Implementation and multicenter validation is needed before widespread application.

The role of tumor necrosis factor (TNF) in regulating various phases of the antiviral T-cell response is incompletely understood. Additionally, despite strong evidence ascribing a role for TNF in protecting against T-cell-dependent autoimmunity, the underlying mechanisms are still obscure. To address these issues, we have investigated the role of tumor necrosis factor receptors (TNFRs) I (p55R) and II (p75R) in regulating CD8 T-cell responses to lymphocytic choriomeningitis virus (LCMV) with wild-type, p55R-deficient (p55 ؊/؊ ), p75R-deficient (p75 ؊/؊ ), and p55R-and p75R-deficient (DKO) mice. Loss of p55R increased the number of memory CD8 T cells to only one of the two immunodominant epitopes, and p75R deficiency had a minimal impact on the T-cell response to LCMV. Strikingly, deficiency of both p55R and p75R had a more dramatic effect on the LCMV-specific CD8 T-cell response; in the DKO mice, as a sequel to enhanced expansion and a reduction in contraction of CD8 T cells, there was a substantial increase in the number of memory CD8 T cells (specific to the two immunodominant epitopes). While the majority of LCMV-specific memory CD8 T cells in wild-type mice were CD62L hi CCR7 hi (central memory), a major proportion of memory CD8 T cells in DKO mice were CD62L lo CCR7 hi . TNFR deficiency did not affect the proliferative renewal of memory CD8 T cells. Taken together, these data suggested that TNFRs p55R and p75R have overlapping roles in downregulating CD8 T-cell responses and establishment of immune homeostasis during an acute viral infection.