Helicobacter pylori chronically colonizes the stomach and duodenum and causes peptic ulcers or gastric adenocarcinoma in 10 to 20% of infected individuals. We hypothesize that the inability of patients to clear H. pylori infections is a consequence of active suppression of the immune response. Here we show that H. pylori-infected individuals have increased frequencies of CD4؉ CD25 high T cells in both the stomach and duodenal mucosa compared to uninfected controls. These cells have the phenotype of regulatory T cells, as they express The gastrointestinal mucosa is in constant contact with both harmless and harmful antigens. The immune system has to discriminate between these antigens to maintain a balance between active defense and the prevention of immunopathology. In mouse models, naturally occurring CD4 ϩ CD25 ϩ regulatory T cells (T reg cells) have been implicated in playing an important role in suppressing immune responses to the normal intestinal flora (28) as well as to pathogens (22,25). However, little is currently known about the role of T reg cells in the human gastrointestinal mucosa.Most studies of human T reg cells have been performed with cells isolated from peripheral blood (2, 17, 32), but CD4 ϩ CD25ϩ cells with suppressor activity have also been demonstrated in the thymus (29), cord blood (36), synovial fluid (4), tonsils (32), and a few types of tumors (19,37). Human T cells have a more variable expression of CD25 (the interleukin-2 receptor ␣-chain) than do mouse T cells, and only those that express CD25 with the highest intensities (CD25 high ) are suppressive (2, 4). T cells expressing intermediate levels of CD25 (CD25 low ) are instead activated effector or memory T cells and lack a regulatory function. T reg cells suppress the activity of other T cells via a contact-dependent mechanism, but the molecules directly mediating this suppression have still not been clearly identified (22). However, the Foxp3 gene (FOXP3 in humans), which encodes the transcription factor scurfin, has recently been demonstrated to be a key regulatory gene for the development and function of T reg cells (10,15,16). Humans with defects in the FOXP3 gene experience strong activation of the immune system, leading to multiorgan autoimmune disease, inflammatory bowel disease, allergies, and severe infections, collectively known as the IPEX syndrome (immune dysregulation, polyendocrinopathy, enteropathy, X-linked inheritance syndrome) (11). FOXP3/Foxp3 is expressed by CD4 ϩ CD25ϩ T reg cells in humans and mice, and the transduction of CD25 Ϫ cells from mice with this gene converts the cells into regulatory cells. Although recent data indicate that FOXP3 gene expression can be induced in CD25Ϫ cells under special conditions (5, 9, 33, 34), these induced FOXP3-expressing cells also have a suppressive capacity, suggesting that a tight link exists between FOXP3 expression and a regulatory function.We are currently investigating the role of T reg cells in chronic Helicobacter pylori infection (20,25). Although H. pylori colo...

This paper addresses the problem of simultaneous localization and mapping (SLAM) by a mobile robot. An incremental SLAM algorithm is introduced that is derived from multigrid methods used for solving partial differential equations. The approach improves on the performance of previous relaxation methods for robot mapping, because it optimizes the map at multiple levels of resolution. The resulting algorithm has an update time that is linear in the number of estimated features for typical indoor environments, even when closing very large loops, and offers advantages in handling nonlinearities compared with other SLAM algorithms. Experimental comparisons with alternative algorithms using two well-known data sets and mapping results on a real robot are also presented

SummaryWe demonstrate that humans have a phenotypically and functionally distinct subset of B lymphocytes that express the interleukin (IL)-2 receptor (IL-2R) a-chain, cluster of differentiation (CD) 25. We found that one-third of the circulating CD20 + B cells expressed CD25 and, using

Highlights d Granzyme B + CD8 + T cells accumulate in the brain after traumatic brain injury (TBI) d Brain CD8 + T cells contribute to chronic motor deficits and myelin pathology d Deficiency/depletion of CD8 + T cells promotes neurological recovery following TBI d B cells and autoreactive antibodies appear to play a regulatory role in TBI

Background -Bronchial inflammation in chronic bronchitis has not been characterised as well as in asthma. The present study was undertaken to assess whether a characteristic pattern of bronchial inflammatory markers could be found in patients with chronic bronchitis. Methods -Bronchoscopy with bronchial lavage was performed in 42 patients with chronic bronchitis and in 13 healthy controls. Twenty three of the patients had non-obstructive chronic bronchitis and 19 had chronic bronchitis and chronic obstructive pulmonary disease (COPD). Eighteen of the patients with bronchitis had recurrent infective exacerbations and 24 did not. Intrabronchial bacterial cultures were taken with a protected specimen brush. Results -Increased activity ofneutrophils, fibroblasts, and eosinophils was found in the patients with chronic bronchitis as assessed by the levels of myeloperoxidase (MPO) and interleukin-8 (IL-8), hyaluronan, and eosinophil cationic protein (ECP), respectively. The levels of tryptase did not differ from the controls. High correlations were found between the levels of MPO and IL-8, as well as ECP and IL-8. No differences were found between the patients with COPD and those with nonobstructive chronic bronchitis. Conclusions -Recruitment and activation of both neutrophils and eosinophils seem to be a characteristic ofchronic bronchitis. This activation is associated with IL-8. The patients with intrabronchial cultures of Streptococcus pneumoniae had the highest individual levels of MPO, ECP, and IL-8 of all subjects in the study, indicating that colonisation with Spneumoniae could promote bronchial inflammation. (Thorax 1995;50:360-365)