To study the cellular infiltrate that occurs within the airways of infants with respiratory syncytial virus bronchiolitis, samples of airways secretions were obtained by bronchial lavage from the lower respiratory tract of infants ventilated for this condition and from the upper airway of non-intubated infants with this disorder using nasopharyngeal aspirates.Cytospin samples were prepared so that differential cell counts could be performed on the cells obtained and alkaline phosphatase-antialkaline phosphatase immunocytochemical analysis of lymphocyte subsets was carried out using a panel of monoclonal antibodies, which included anti-CD3, anti-CD4, anti-CD8, anti-CD19, and anti-TcR-y.Results from the lower and upper airways were similar. Large numbers of inflammatory cells were obtained, of which neutrophils accounted for a median of 93%/o in the upper airway and 76% in the lower airway. The numbers of CD8 positive cells detected were small and consistently less than CD4 positive cells, median CD4:CD8 ratios being 22*5:1 and 15:1 for the lower and upper airways. CD19 positive cells were rarely observed and no y8 positive lymphocytes were detected.These results indicate that neutrophils probably play a major part in causing symptoms in these infants. They do not support the concept that excessive lymphocyte mediated cytotoxic activity is principally responsible for the pathology in respiratory syncytial virus bronchiolitis. (Arch Dis Child 1994; 71: 428-432) The respiratory syncytial virus is unique in its ability to cause yearly epidemics of respiratory disease.1 2 As a result almost all infants will have been infected by the virus by the second year of life and, of these, 05-2% develop acute bronchiolitis severe enough to be admitted to hospital. Results from studies using a formalin inactivated virus3 and other more recent attempts to produce a vaccine suggest that it is unlikely that we will be able to effectively prevent this distressing illness until the immunological mechanisms involved in the disease process, including those aspects conferring protection, are clarified.

Diverse gram-negative bacterial cells communicate with each other by using diffusible N-acyl homoserine lactone (AHL) signal molecules to coordinate gene expression with cell population density. Accumulation of AHLs above a threshold concentration renders the population “quorate,” and the appropriate target gene is activated. In pathogenic bacteria, such as Pseudomonas aeruginosa, AHL-mediated quorum sensing is involved in the regulation of multiple virulence determinants. We therefore sought to determine whether the immune system is capable of responding to these bacterial signal molecules. Consequently the immunomodulatory properties of the AHLsN-(3-oxododecanoyl)-l-homoserine lactone (OdDHL) and N-(3-oxohexanoyl)-l-homoserine lactone (OHHL) were evaluated in murine and human leukocyte immunoassays in vitro. OdDHL, but not OHHL, inhibited lymphocyte proliferation and tumor necrosis factor alpha production by lipopolysaccharide-stimulated macrophages. Furthermore, OdDHL simultaneously and potently down-regulated the production of IL-12, a Th-1-supportive cytokine. At high concentrations (>7 × 10−5 M) OdDHL inhibited antibody production by keyhole limpet hemocyanin-stimulated spleen cells, but at lower concentrations (<7 × 10−5 M), antibody production was stimulated, apparently by increasing the proportion of the immunoglobulin G1 (IgG1) isotype. OdDHL also promoted IgE production by interleukin-4-stimulated human peripheral blood mononuclear cells. These data indicate that OdDHL may influence the Th-1–Th-2 balance in the infected host and suggest that, in addition to regulating the expression of virulence determinants, OdDHL may contribute to the pathogenesis of P. aeruginosa infections by functioning as a virulence determinant per se.

Lymphocytes and macrophages are present in the normal intestinal lamina propria, separated from the epithelial monolayer by the basement membrane. There is evidence for movement of mononuclear cells through the lamina propria, entering from the systemic circulation and exiting via lymphatic channels. The goal of our studies was to investigate the capacity of cells to migrate out from the lamina propria into the lumen following the loss of surface epithelial cells. An in vitro model was therefore established in which normal human intestinal mucosal samples, denuded of the surface epithelium, were maintained in culture. Electron microscopy showed that during culture, large numbers (>2 x 10(6)/g tissue per 24 h) of cells migrated out of the lamina propria via discrete 'tunnels' which were in continuity with pores (diameter <4 microm) in the basement membrane. The emigrating cells were T cells (68.5 +/- 5.1%), macrophages (10.5 +/- 1.3%) and eosinophils (7.1 +/- 1.3%). Our studies have therefore demonstrated, for the first time, the capacity for large numbers of lymphocytes, macrophages and eosinophils to migrate out of the lamina propria, via basement membrane pores. We postulate that such emigration of cells occurs in vivo following the loss of surface epithelial cells due to injury, and could represent an important form of host defence against luminal microorganisms and also facilitate wound repair by enhancing restitution by neighbouring epithelial cells, via peptide factors.

The EarlyCDT-Lung test is a high specificity blood-based autoantibody biomarker that could contribute to predicting lung cancer risk. Here we report on the results of a phase IV biomarker evaluation of whether using the EarlyCDT-Lung test and any subsequent CT scanning to identify those at high risk of lung cancer reduces the incidence of patients with stage III/IV/Unspecified lung cancer at diagnosis, compared with the standard clinical practice at the time the study began.ECLS was a randomised controlled trial of 12 208 participants at risk of developing lung cancer in Scotland. The intervention arm received the EarlyCDT-Lung test and, if test positive, low-dose CT scanning six-monthly for up to 2 years. EarlyCDT-Lung test negative and control arm participants received standard clinical care. Outcomes were assessed at 2 years post-randomisation using validated data on cancer occurrence, cancer staging, mortality and comorbidities.At 2 years, 127 lung cancers were detected in the study population (1.0%).In the intervention arm, 33/56 (58.9%) lung cancers were diagnosed at stage III/IV compared to 52/71 (73.2%) in the control arm. The hazard ratio for stage III/IV presentation was 0.64 (95% confidence interval 0.41, 0.99). There were non-significant differences in lung cancer and all-cause mortality after 2 years.ECLS compared EarlyCDT-Lung plus CT screening to standard clinical care (symptomatic presentation), and was not designed to assess the incremental contribution of the EarlyCDT-Lung test. The observation of a stage-shift towards earlier-stage lung cancer diagnosis merits further investigations to evaluate whether the EarlyCDT-Lung test adds anything to the emerging standard of LDCT.

C. difficile infection (CDI) is rarely reported in cystic fibrosis (CF) patients despite frequent hospitalisations and antibiotic usage. Conversely, the prevalence of CDI in inflammatory bowel disease (IBD) has received increased attention. We investigated components of the IgG-specific humoral immune response to C. difficile toxins A and B in patients with C. difficile-associated diarrhoea (CDAD), IBD patients with CDI, CF patients and healthy controls. Serum anti-toxin IgG was determined by ELISA. Circulating antigen-activated B-cells were investigated using Alexa Fluor 488-labelled toxin A and assessed by flow cytometry. Following induction of differentiation of memory B-cells, toxin A- and B-specific antibody secreting cells (ASCs) were quantified using ELISpot. We present the first data showing levels of serum anti-toxin A and B antibodies were significantly higher in patients with CF (without a history of CDI) than in CDAD patients and were stably maintained over time. Notably, the CDAD patients were significantly older than the CF patients. We also show that circulating toxin A-specific memory B-cells (IgD-negative) can be detected in CDAD patients [0.92 (0.09–1.78)%], and were prominent (5.64%, 1.14%) in two CF patients who were asymptomatic carriers of C. difficile. There was correlation between toxin A- and B-specific ASCs, with significantly higher proportions of the latter seen. In some with CDAD, high serum antibody levels were seen to only one of the two toxins. Mucosal secretion of toxin-specific IgG was detected in an additional group of IBD patients with no history of CDI. We conclude that enhanced and stable humoral immune responses to toxins A and B may protect CF and some IBD patients against CDI. The impaired ability to generate strong and/or sustained toxin-specific antibody and memory B-cell responses may increase susceptibility of older patients to CDI and highlight the need to investigate the role of immune senescence in future studies.

No abstract

No abstract

No abstract