These guidelines are a consensus work of a considerable number of members of the immunology and flow cytometry community. They provide the theory and key practical aspects of flow cytometry enabling immunologists to avoid the common errors that often undermine immunological data. Notably, there are comprehensive sections of all major immune cell types with helpful Tables detailing phenotypes in murine and human cells. The latest flow cytometry techniques and applications are also described, featuring examples of the data that can be generated and, importantly, how the data can be analysed. Furthermore, there are sections detailing tips, tricks and pitfalls to avoid, all written and peer‐reviewed by leading experts in the field, making this an essential research companion.

This study dissects the contribution of TLR signaling to intestinal tumorigenesis. MyD88 signaling, known to be required for tumorigenesis in Apcmin/+ mice, is shown to be triggered by ligands from the microflora. MyD88-mediated activation of the MEK-ERK cascade stabilizes c-Myc by preventing its ubiquitin-mediated degradation. The findings link oncogenic c-Myc function to immune signaling and uncover MEK inhibition as a new therapeutic strategy to treat intestinal tumors. Toll-like receptor (TLR) signaling is essential for intestinal tumorigenesis in Apcmin/+ mice, but the mechanisms by which Apc enhances tumor growth are unknown. Here we show that microflora-MyD88-ERK signaling in intestinal epithelial cells (IECs) promotes tumorigenesis by increasing the stability of the c-Myc oncoprotein. Activation of ERK (extracellular signal–related kinase) phosphorylates c-Myc, preventing its ubiquitination and subsequent proteasomal degradation. Accordingly, Apcmin/+/Myd88−/− mice have lower phospho-ERK (p-ERK) levels and fewer and smaller IEC tumors than Apcmin/+ mice. MyD88 (myeloid differentiation primary response gene 88)-independent activation of ERK by epidermal growth factor (EGF) increased p-ERK and c-Myc and restored the multiple intestinal neoplasia (Min) phenotype in Apcmin/+/Myd88−/− mice. Administration of an ERK inhibitor suppressed intestinal tumorigenesis in EGF-treated Apcmin/+/Myd88−/− and Apcmin/+ mice and increased their survival. Our data reveal a new facet of oncogene-environment interaction, in which microflora-induced TLR activation regulates oncogene expression and related IEC tumor growth in a susceptible host.

We tested the hypothesis that the presence of bacterial DNA (bactDNA) in ascitic fluid and serum is associated with decreased survival in patients with cirrhosis. In a prospective, multicenter study, we analyzed the clinical evolution of 156 patients with cirrhosis and ascites (first or recurrence) with lower than 250 polymorphonuclear cells (PMN)/μL, negative ascites bacteriological culture, and absence of other bacterial infections being admitted for evaluation of large-volume paracentesis, according to the presence of bactDNA at admission. Survival, causes of death, and successive hospital admissions were determined during a 12-month follow-up period. BactDNA was detected in 48 patients. The most prevalent identified bactDNA corresponded to Escherichia coli (n = 32/48 patients, 66.6%). Patients were followed for 12 months after inclusion and in this period 34 patients died: 16 of 108 (15%) bactDNA negative versus 18 of 48 (38%) bactDNA positive ( P = 0.003). The most frequent cause of death was acute-on-chronic liver failure in both groups (7/16 and 9/18 in patients without or with bactDNA, respectively), although more prevalent in the first month of follow-up in patients with presence of bactDNA (0 versus 4/7). When considering patients with model for end-stage liver disease (MELD) score less than 15, mortality was significantly higher in those with presence of bactDNA. Spontaneous bacterial peritonitis developed similarly in patients with or without bactDNA at admission. Conclusion : The presence of bactDNA in a patient with cirrhosis during an ascitic episode is an indicator of poor prognosis. This fact may be related to the development of acute-on-chronic liver failure at short term and does not predict the development of spontaneous bacterial peritonitis. (Hepatology 2008;48:1924-1931.)

Bacterial infections and severity of associated inflammatory reaction influence prognosis in patients with advanced cirrhosis. We compared the innate immune response to bacterial DNA (bactDNA) translocation with that caused by viable bacteria translocation in patients with spontaneous bacterial peritonitis and the relationship between the cytokine response and serum levels of bactDNA. The bactDNA translocation was investigated in 226 patients with cirrhosis and noninfected ascites, 22 patients with spontaneous bacterial peritonitis, and 10 patients with ascites receiving continuous norfloxacin. Serum and ascitic fluid tumor necrosis factor α, interferon-γ, interleukin-12, and nitric oxide metabolites were measured via enzyme-linked immunosorbent assay. Bacterial genomic identifications were made via amplification and sequencing of the 16S ribosomal RNA gene and digital quantization with DNA Lab-on-chips. The bactDNA was present in 77 noninfected patients (34%) and in all cases of spontaneous bacterial peritonitis, even in those with culture-negative ascitic fluid. No patient receiving norfloxacin showed bactDNA translocation. Levels of all cytokines were similar in patients with bactDNA translocation or spontaneous bacterial peritonitis and significantly higher than in patients without bactDNA or in those receiving norfloxacin. Serum bactDNA concentration paralleled levels of all cytokines and nitric oxide in a series of patients with bactDNA translocation or spontaneous bacterial peritonitis followed during 72 hours. Antibiotic treatment in the series of patients with spontaneous bacterial peritonitis did not abrogate bactDNA translocation in the short term. Conclusion: bactDNA translocation-associated cytokine response is indistinguishable from that in patients with spontaneous bacterial peritonitis and is dependent on bactDNA concentration. Norfloxacin abrogates bactDNA translocation and cytokine response.