Eosinophils are potent effector cells that are recruited to sites of inflammation. However, in some tissues, in particular in the gastrointestinal tract, eosinophils constitute an abundant leukocyte population also under homeostatic conditions. The lack of suitable isolation protocols restricted the analysis of these cells to histological assessment of cell numbers while important aspects of their phenotype, turnover, and functions remain unresolved. In this study, we report a protocol that allows the quantitative isolation of intestinal eosinophils. We characterized small intestinal eosinophils by flow cytometry as SSChighCD11b+CD11c+CCR3+Siglec-F+ cells. Intestinal eosinophils resembled eosinophils isolated from thymus and uterus but differed from eosinophils isolated from lung or blood. Eosinophils in intestine, thymus, and uterus showed in vivo a markedly higher life time compared with eosinophils present in lung and blood measured by incorporation of BrdU. This indicates that under steady-state conditions homeostasis of eosinophils is controlled by regulation of cell survival. Intestinal eosinophils are severely reduced in the intestines of Rag-2/common γ-chain double-deficient mice but not Rag-2-deficient mice, correlating with differential expression of GM-CSF and CCL11 in both mouse strains. Moreover, under steady-state conditions, intestinal eosinophils constitutively express high levels of the common γ-chain transcripts compared with lung eosinophils as well as eosinophils present under inflammatory conditions. These observations reveal a hitherto unrecognized diversity in phenotypic and functional properties of eosinophils and suggest that tissue-specific common γ-chain-dependent signals might profoundly affect eosinophil function and homeostasis.

Bronchoscopy in children is relatively safe. Nevertheless, adverse events can occur and knowledge of risk factors may help prevent complications.

PIG is associated with alveolar growth abnormalities and has to be considered in all newborns with unexplained respiratory distress. Apparent treatment benefit of glucocorticosteroids needs to be evaluated systematically.

Background Multiple breath washout (MBW) is increasingly used in the clinical assessment of patients with cystic fibrosis (CF). Guidelines for MBW quality control (QC) were developed primarily for retrospective assessment and central overreading. We assessed whether real‐time QC of MBW data during the measurement improves test acceptability in the clinical setting. Methods We implemented standardized real‐time QC and reporting of MBW data at the time of the measurement in the clinical pediatric lung function laboratory in Bern, Switzerland, in children with CF aged 4–18 years. We assessed MBW test acceptability before (31 tests; 89 trials) and after (32 tests; 96 trials) implementation of real‐time QC and compared agreement between reviewers. Further, we assessed the implementation of real‐time QC at a secondary center in Zurich, Switzerland. Results Before the implementation of real‐time QC in Bern, only 58% of clinical MBW tests were deemed acceptable following retrospective QC by an experienced reviewer. After the implementation of real‐time QC, MBW test acceptability improved to 75% in Bern. In Zurich, after the implementation of real‐time QC, test acceptability improved from 38% to 70%. Further, the agreement between MBW operators and an experienced reviewer for test acceptability was 84% in Bern and 93% in Zurich. Conclusion Real‐time QC of MBW data at the time of measurement is feasible in the clinical setting and results in improved test acceptability.