Airway inflammation in asthma and chronic obstructive pulmonary disease with special emphasis on the antigen-presenting dendritic cell: influence of treatment with fluticasone propionate

Oscillometry in Lung Function Assessment: A Comprehensive Review of Current Insights and Challenges

Oscillometry, a non-invasive technique for assessing lung function, has gained significant recognition and importance in modern pulmonary medicine. This comprehensive review thoroughly explores its principles, applications, advantages, limitations, recent innovations, and future directions. Oscillometry's primary strength lies in its ability to offer a holistic assessment of lung mechanics. Unlike traditional spirometry, oscillometry captures the natural airflow during quiet breathing, making it suitable for patients of all ages and those with severe respiratory conditions. It provides a comprehensive evaluation of airway resistance, reactance, and compliance, offering insights into lung function that were previously challenging to obtain. In clinical practice, oscillometry finds extensive application in diagnosing and managing respiratory diseases. It plays a pivotal role in asthma, chronic obstructive pulmonary disease (COPD), and interstitial lung diseases. By detecting subtle changes in lung function before symptoms manifest, oscillometry facilitates early interventions, improving disease management and patient outcomes. Oscillometry's non-invasive and patient-friendly nature is precious in pediatric care, where traditional spirometry may be challenging for young patients. It aids in diagnosing and monitoring pediatric respiratory disorders, ensuring that children receive the care they need from an early age. Despite its many advantages, oscillometry faces challenges, such as the need for standardized protocols and the complexity of data interpretation. However, ongoing efforts to establish global standards and provide education and training for healthcare professionals aim to address these issues. Looking ahead, oscillometry holds great promise in the field of personalized medicine. With its ability to tailor treatment plans based on individualized lung function data, healthcare providers can optimize therapy selection and dosing, ultimately improving patient care and quality of life. In conclusion, oscillometry is poised to play an increasingly pivotal role in modern pulmonary medicine. As standardization efforts continue and technology evolves, it is an indispensable tool in the clinician's arsenal for diagnosing, managing, and personalizing respiratory care, ultimately leading to improved patient outcomes and better respiratory health.

Attenuated asthma phenotype in mice with a fetal-like antigen receptor repertoire

We hypothesized that the scarcity of N-nucleotides might contribute to the inability of the neonate to mount a robust allergic immune response. To test this, we used terminal deoxyribunucleotidyl Transferase deficient (TdT^-/-) mice, which express "fetal-like" T cell receptor and immunoglobulin repertoires with largely germline-encoded CDR3 regions. Intraperitoneal sensitization was followed by aerosol provocation with either PBS or the allergen OVA in both TdT^-/- mice and wild-type mice to develop allergic respiratory inflammation. The effects of this procedure were investigated by lung function test, immunological analysis of serum and brochoalveolar lavage. The local T_H2 cytokine milieu was significantly attenuated in TdT^-/- mice. Within this group, the induction of total IgE levels was also significantly reduced after sensitization. TdT^-/- mice showed a tendency toward reduced eosinophilic inflow into the bronchial tubes, which was associated with the elimination of respiratory hyperreactivity. In conclusion, in a murine model of allergic airway inflammation, the expression of fetal-like antigen receptors was associated with potent indications of a reduced ability to mount an asthma phenotype. This underlines the importance of somatically-generated antigen-receptor repertoire diversity in type one allergic immune responses and suggests that the fetus may be protected from allergic responses, at least in part, by controlling N addition.

The Association between Vigorous Physical Activity and Stress in Adolescents with Asthma

Asthma is a very common condition that affects 5-10% of the global population, and its prevalence is increasing. Vigorous physical activity (PA) is effective in improving cardiorespiratory fitness and managing stress. This study aimed to investigate the association between vigorous PA and stress among Korean adolescents with asthma using large-scale survey data. The questionnaire data of 57,303 adolescents were analyzed using raw data from the 2019 Korea Youth Risk Behavior Web-Based Survey. We performed logistic regression analysis to calculate the stress odds ratios (ORs) and 95% confidence intervals (CIs) for asthma and non-asthma groups using models 1 and 2. We also performed logistic regression analysis to calculate the stress OR for the asthma group with vigorous PA and non-vigorous PA using models 1, 2, and 3. Model 1 was adjusted for age, sex, obesity, smoking, and alcohol status; model 2 was further adjusted for household income, academic achievement, and comorbidities. Model 3 was further adjusted for moderate activity and resistance exercise. The OR of stress was 20% higher in the asthma group than in the non-asthma group (p < 0.05). In the fully adjusted models, the OR for the non-asthma group with vigorous PA versus non-vigorous PA was 0.89 (95% CI: 0.84-0.94). However, the OR for the asthma group with vigorous PA versus non-vigorous PA was 0.70 (95% CI: 0.57-0.86), indicating that adolescents who engage in vigorous PA had lower stress in the asthma group (p < 0.05). This study demonstrated that adolescents with asthma had higher stress levels than those without asthma; however, vigorous PA was associated with lower stress. These effects were more pronounced in adolescents with asthma.

Metabolic differences between bronchial epithelium from healthy individuals and patients with asthma and the effect of bronchial thermoplasty

BACKGROUND

Asthma is a heterogeneous disease with differences in onset, severity, and inflammation. Bronchial epithelial cells (BECs) contribute to asthma pathophysiology.

OBJECTIVE

We determined whether transcriptomes of BECs reflect heterogeneity in inflammation and severity in asthma, and whether this was affected in BECs from patients with severe asthma after their regeneration by bronchial thermoplasty.

METHODS

RNA sequencing was performed on BECs obtained by bronchoscopy from healthy controls (n = 16), patients with mild asthma (n = 17), patients with moderate asthma (n = 5), and patients with severe asthma (n = 17), as well as on BECs from treated and untreated airways of the latter (also 6 months after bronchial thermoplasty) (n = 23). Lipidome and metabolome analyses were performed on cultured BECs from healthy controls (n = 7); patients with severe asthma (n = 9); and, for comparison, patients with chronic obstructive pulmonary disease (n = 7).

RESULTS

Transcriptome analysis of BECs from patients showed a reduced expression of oxidative phosphorylation (OXPHOS) genes, most profoundly in patients with severe asthma but less profoundly and more heterogeneously in patients with mild asthma. Genes related to fatty acid metabolism were significantly upregulated in asthma. Lipidomics revealed enhanced levels of lipid species (phosphatidylcholines, lysophosphatidylcholines. and bis(monoacylglycerol)phosphate), whereas levels of OXPHOS metabolites were reduced in BECs from patients with severe asthma. BECs from patients with mild asthma characterized by hyperresponsive production of mediators implicated in neutrophilic inflammation had decreased expression of OXPHOS genes compared with that in BECs from patients with mild asthma with normoresponsive production. BECs obtained after thermoplasty had significantly increased expression of OXPHOS genes and decreased expression of fatty acid metabolism genes compared with BECs obtained from untreated airways.

CONCLUSION

BECs in patients with asthma are metabolically different from those in healthy individuals. These differences are linked with inflammation and asthma severity, and they can be reversed by bronchial thermoplasty.

Possible therapeutic effects of Crocus sativus stigma and its petal flavonoid, kaempferol, on respiratory disorders

CONTEXT

Crocus sativus L. (Iridaceae), or saffron, has been used as food additives and spices. In the traditional medicine of Iran, C. sativus has been used for the treatment of liver disorders, coughs, and as an anti-inflammatory agent for eyes.

OBJECTIVE

The current study reviewed the possible therapeutic effects of C. sativus stigma and its petal flavonoid (kaempferol) on respiratory disorders with several mechanisms such as anti-inflammatory, and smooth muscle relaxant effects.

MATERIALS AND METHODS

This review article searched databases including PubMed, Google Scholar, and ScienceDirect, up to November 2019. The keywords including; 'Crocus sativus', 'saffron', 'kaempferol', 'airway inflammation', and 'smooth muscle relaxant' were searched.

RESULTS

C. sativus reduced nitric oxide (NO), inducible nitric oxide synthase (iNOS) levels and inflammatory cytokines in the lung tissue. Saffron and kaempferol reduced white blood cells (WBCs) and the percentage of neutrophils and eosinophils in bronchoalveolar lavage fluid. Moreover, saffron reduced tracheal responsiveness to methacholine and ovalbumin on tracheal smooth muscles. In addition, kaempferol reduced the total leukocyte and eosinophil counts similar to the effect of dexamethasone and also showed relaxant effects on smooth muscle.

DISCUSSION AND CONCLUSION

Crocus sativus and its petal flavonoid, kaempferol, showed relatively potent therapeutic effects on respiratory disorders by relaxation of tracheal smooth muscles via stimulatory or blocking effects on β-adrenoceptor and muscarinic receptors, respectively. Saffron and kaempferol also decreased production of NO, inflammatory cytokines and chemokines in respiratory systems.

Anti-Asthmatic Effects of Portulaca Oleracea and its Constituents, a Review

OBJECTIVES

The medicinal plants are believed to enhance the natural resistance of the body to infections. Some of the main constituents of the plant and derived materials such as, proteins, lectins and polysaccharides have anti-inflammatory effects. Portulaca oleracea (P. oleracea) were used traditionally for dietary, food additive, spice and various medicinal purposes. This review article is focus on the anti-asthmatic effects of P. oleracea and its constituents.

METHODS

Various databases, such as the PubMed, Scopus, and Google Scholar, were searched the keywords including "Portulaca oleracea", "Quercetin", "Anti-inflammatory", "Antioxidant", "Cytokines", "Smooth muscle ", and " Relaxant effects " until the end of Jul 2018.

RESULTS

P. oleracea extracts and its constituents increased IFN-γ, IL-2, IFNγ/IL-4 and IL- 10/IL-4 ratio, but decreased secretion of TNF-α, IL-4 and chemokines in both in vitro and in vivo studies. P. oleracea extracts and quercetin also significantly decreased production of NO, stimulated β-adrenoceptor and/or blocking muscarinic receptors in tracheal smooth muscles. Conclusion: P. oleracea extracts and quercetin showed relatively potent anti-asthmatic effects due to decreased production of NO, inflammatory cytokines and chemokines, reduced oxidant while enhanced antioxidant markers, and also showed potent relaxant effects on tracheal smooth muscles via stimulatory on β-adrenoceptor or/and blocking muscarinic receptors.

Nasobronchial interaction

Upper and lower airways can be considered as a unified morphofunctional unit. In this paper, nasobronchial interactions are evaluated based on literature.To discuss nasobronchial interactions, literature review from PubMed since 1982 is evaluated. Data base was including the terms “nasobronchial interaction, nasal and bronchial”. Asthma and rhinosinusitis may be associated with environmental factors and immunological predisposition. Treatment of rhinosinusitis may decrease asthma exacerbations. It was concluded that “one airway, one disease”-concept may be accepted when considering naso-bronchial interaction. Asthma treatment should also mean treating the nose as good as treating patients with nasal symptoms. To reach the succesful results ıt should be associated with evaluation of lung functions.

Modulation of FLT3 signaling targets conventional dendritic cells to attenuate acute lung injury

Conventional dendritic cells (cDCs) have been reported to participate in the pathophysiology of acute lung injury (ALI). Fms-like tyrosine kinase 3 (FLT3) signaling represents a highly specific pathway for the manipulation of cDCs in vivo. The purpose of this study was to clarify the effect of FLT3 signaling on the accumulation and maturation of pulmonary cDCs, and whether inhibition of FLT3 signaling may attenuate acute lung inflammation and lung injury. C57BL/6 mice were pretreated with FLT3-ligand (FLT3L) and lestaurtinib separately for five consecutive days. A murine model of ALI was subsequently generated by intra-tracheal instillation of lipopolysaccharide (LPS) and lung specimens were harvested 24 h later. Flow cytometry was conducted to measure the accumulation and maturation of pulmonary cDCs. IL-6, IFN-γ, IL-4, MPO activity and transcription factor T-bet/GATA-3 mRNA ratio were quantified to evaluate lung inflammation. Lung injury was estimated by lung wet weight/body weight ratio (LWW/BW) and histopathological analysis. LPS challenge resulted in rapid accumulation and maturation of pulmonary cDCs. FLT3L pretreatment further stimulated the accumulation and maturation of pulmonary cDCs, leading to a markedly increased LWW/BW and aggravated lung histopathology. Meanwhile, lung MPO activity, T-bet/GATA-3 mRNA ratio and concentrations of IL-6 and IFN-γ were elevated by FLT3L administration. In contrast, lestaurtinib pretreatment inhibited the accumulation and maturation of pulmonary cDCs, leading to a significantly decreased LWW/BW and improved lung histopathology. Lestaurtinib administration also suppressed lung MPO activity, T-bet/GATA-3 mRNA ratio and production of IL-6 and IFN-γ. Our findings show that FLT3 signaling ameliorates ALI by regulating the accumulation and maturation of pulmonary cDCs, suggesting an innovative pharmacotherapy for ALI.

Between a cough and a wheeze: dendritic cells at the nexus of tobacco smoke-induced allergic airway sensitization

Exposure to cigarette smoke represents a major risk factor for the development of asthma. Enhanced sensitization toward allergens has been observed in humans and laboratory animals exposed to cigarette smoke. Pulmonary dendritic cells (DCs) are crucially involved in sensitization toward allergens and play an important role in the development of T helper (Th)2-mediated allergic airway inflammation. We propose the concept that aberrant DC activation forms the basis for the deviation of the lung's default tolerogenic response toward allergic inflammation when harmless antigens are concomittantly inhaled with tobacco smoke. This review will summarize evidence suggesting that tobacco smoke can achieve this effect by providing numerous triggers of innate immunity, which can profoundly modulate airway DC biology. Tobacco smoke can affect the airway DC network either directly or indirectly by causing the release of DC-targeted mediators from the pulmonary tissue environment, resulting in the induction of a Th2-oriented pathological immune response. A thorough knowledge of the molecular pathways involved may open the door to novel approaches in the treatment of asthma.

CC chemokine receptor 5 and CXC chemokine receptor 6 expression by lung CD8+ cells correlates with chronic obstructive pulmonary disease severity

Chronic obstructive pulmonary disease (COPD) is a progressive disease associated with a cellular inflammatory response. CD8(+) T cells are implicated in COPD pathogenesis, and their numbers significantly correlate with the degree of airflow limitation. Dendritic cells (DCs) are important sentinel immune cells, but little is known about their role in initiating and maintaining the CD8 T-cell response in COPD. To investigate the mechanisms for CD8(+) T-cell recruitment to the lung, we used resected human lung tissue to analyze chemokine receptor expression by CD8(+) T cells and chemokine production by CD1a(+) DCs. Among 11 surveyed chemokine receptors, only CC chemokine receptor (CCR5), CXC chemokine receptor (CXCR) 3, and CXCR6 correlated with COPD severity as defined by criteria from the Global Initiative for Chronic Obstructive Lung Disease. The CD8(+) T cells displayed a Tc1, CD45RA(+) effector memory phenotype. CD1a(+) DCs produced the respective ligands for CCR5 and CXCR3, CCL3 and CXCL9, and levels correlated with disease severity. CD1a(+) DCs also constitutively expressed the CXCR6 ligand, CXCL16. In conclusion, we have identified major chemokine elements that potentially mediate CD8(+) T-cell infiltration during COPD progression and demonstrated that CD1a(+) mucosal-associated DCs may sustain CD8(+) T-cell recruitment/retention. Chemokine targeting may prove to be a viable treatment approach.

Density of dendritic cells in the human tracheal mucosa is age dependent and site specific

BACKGROUND

The mucosal immune system undergoes extensive changes in early childhood in response to environmental stimuli. Dendritic cells (DC) play a major role in the development of the immune system. However, few data exist on the influence of continuous environmental stimulation on the distribution and phenotype of human airway DC.

METHODS

Human tissue samples are mostly paraffin embedded which limits the use of several antibodies, and respiratory tissue for cryopreservation is difficult to obtain. Human frozen post mortem tracheal tissue was therefore used for this study. Only samples with epithelial adherence to the basement membrane were included (n = 34). Immunohistochemical staining and sequential overlay immunofluorescence were performed with DC-SIGN and a panel of leucocyte markers co-expressed by DC.

RESULTS

DC detected in the human tracheal mucosa using DC-SIGN correlated with the expression of HLA-DR, co-stimulatory and adhesion molecules. Higher cell densities were found at the ventral tracheal site of patients older than 1 year than in infants in the first year of life.

CONCLUSION

The increasing population of mucosal DC with age could reflect immunological maturation.

Immunotherapy of Murine Malignant Mesothelioma Using Tumor Lysate–pulsed Dendritic Cells

RATIONALE

Exploiting the immunostimulatory capacities of dendritic cells holds great promise for cancer immunotherapy. Currently, dendritic cell-based immunotherapy is evaluated clinically in a number of malignancies, including melanoma and urogenital and lung cancer, showing variable but promising results.

OBJECTIVE

To evaluate if pulsed dendritic cells induce protective immunity against malignant mesothelioma in a mouse model.

METHODS

Malignant mesothelioma was induced in mice by intraperitoneal injection of the AB1 mesothelioma cell line, leading to death within 28 days. For immunotherapy, dendritic cells were pulsed overnight either with AB1 tumor cell line lysate, AB1-derived exosomes, or ex vivo AB1 tumor lysate, and injected either before (Days -14 and -7) at the day of (Day 0) or after (Days +1 and +8) tumor implantation.

MAIN RESULTS

Mice receiving tumor lysate-pulsed dendritic cells before tumor implantation demonstrated protective antitumor immunity with prolonged survival (> 3 months) and even resisted secondary tumor challenge. Tumor protection was associated with strong tumor-specific cytotoxic T-lymphocyte responses. Adoptive transfer of splenocytes or purified CD8+ T lymphocytes transferred tumor protection to unimmunized mice in vivo. When given after tumor implantation in a therapeutic setting, pulsed dendritic cells prevented mesothelioma outgrowth. With higher tumor load and delayed administration after tumor implantation, dendritic cells were no longer effective.

CONCLUSIONS

We demonstrate in this murine model that immunotherapy using pulsed dendritic cells may emerge as a powerful tool to control mesothelioma outgrowth. In the future, immunotherapy using dendritic cells could be used as adjuvant to control local recurrence after multimodality treatment for malignant mesothelioma.

Dendritic cells and the regulation of the allergic immune response

Studies in mouse models of asthma have revealed a critical role for airway dendritic cells in the induction of Th2 sensitization to inhaled allergens. Under some conditions, subsets of dendritic cells can also induce tolerance or Th1 responses to the same allergens, depending on the context in which the antigen is seen. This article discusses various aspects of DC biology as it relates to allergic sensitization and also provides a summary of the recent evidence that dendritic cells function beyond sensitization.

A simple method for the purification of human peripheral blood antigen presenting cells (dendritic cells, monocytes/macrophages, and B lymphocytes)

An adherence method was developed that enriches for antigen presenting cells (dendritic cells, monocytes/macrophages, and B lymphocytes) from peripheral blood mononuclear cell (PBMC) preparations. This method utilizes the cells' natural adherence to polystyrene tissue culture dishes and their subsequent removal with K3EDTA after incubation at 4 degrees, with gentle pipeting. Flow cytometric analysis revealed that on average, the enrichment of CD83+ dendritic cells, CD14+ monocytes/ macrophages, and CD19+ B cells increased by 12.5 to 20, 2, and 4 fold, respectively, compared to their initial numbers present in PBMC preparations. Cell viability, determined by trypan blue exclusion, was between 90 and 98%. After the enrichment procedure, the cells could still be activated by tetanus toxoid and this was shown by flow cytometric analysis, as enhancement of class II major histocompatibility complex (MHC) (31% increase) (after antigen treatment). This is a fast and economical alternative to other established methods for the preparation of pure, functionally competent antigen presenting cells derived from peripheral blood.

Eosinophilic esophagitis in children: immunopathological analysis and response to fluticasone propionate

BACKGROUND & AIMS

Eosinophilic esophagitis (EE) shares symptoms with gastroesophageal reflux disease but has distinctive pathologic features and unknown immunopathology. Treatments with antigen restriction or systemic immunosuppression pose problems with compliance and side effects. Topically applied steroids offer an attractive alternative treatment. The aims of this study were to determine the immunopathologic features of EE and the effectiveness of antigen-specific diet restriction (DR) and topical immunosuppression.

METHODS

A prospective trial was conducted examining the impact of DR and swallowed fluticasone propionate (FP) on pediatric patients with EE. Clinicopathologic features, including immunohistochemical analysis of the esophageal mucosa, were measured before and after treatment.

RESULTS

Immunohistochemical analysis of 11 prospectively identified children showed a significantly greater number of mucosal CD3 and CD8 lymphocytes, as well as CD1a antigen-presenting cells compared with normal controls. DR did not induce clinical improvement in any patients, whereas all children who completed treatment with FP had resolution of symptoms. Posttreatment analysis of proximal and distal esophageal mucosa showed a significant reduction in the number of eosinophils, as well as CD3(+) and CD8(+) lymphocytes compared with pretreatment sections.

CONCLUSIONS

EE is characterized by immunologically active esophageal mucosa. FP, not DR, effectively relieves symptoms. FP significantly reduces mucosal inflammation associated with EE.

Visualization of early APC/T cell interactions in the mouse lung following intranasal challenge

We have used fluorescent latex beads, with or without covalently conjugated OVA, to facilitate study of Ag trafficking in the mouse lung and draining peribronchial lymph node (LN). At 6 h, and up to 48 h after intranasal administration, beads were observed as intracellular clusters in the tissue parenchyma. Flow cytometry of bead-positive (bead(+)) cells from the bronchoalveolar lavage demonstrated that a majority of these cells are CD11c(+), F4/80(+), and CD11b(-). Furthermore, fluorescent microscopy confirmed that a major subset of bead(+) cells in the lung tissue was also CD11c(+). In the draining peribronchial LNs, small numbers of beads were present in the subcapsular sinus as early as 6 h after inhalation. By 12 h and beyond, bead(+) cells had localized exclusively to the LN T zone. OVA-conjugated latex beads, in addition to stimulating brisk proliferation of naive, OVA-specific DO11.10 transgenic T cells in vitro, could also recruit OVA-specific T cells in vivo. In some cases, bead(+) APCs and CD4(+) Th1 cells were found adjacently localized in the lung tissue 6 h after airway challenge. Thus, interactions of bead(+) APCs with Ag-specific CD4(+) T cells occurred earlier in the peripheral airways than these same interactions occurred in the draining peribronchial LN. Lastly, after adoptive transfer, in vitro differentiated Th1 cells accumulated at peripheral sites in the lung tissue and airways before Ag challenge and therefore were ideally positioned to influence subsequent immune reactions of the airway.

Rapid dendritic cell recruitment to the bronchial mucosa of patients with atopic asthma in response to local allergen challenge

BACKGROUND

Airway dendritic cells (DC) play an important role in chronic allergic airway inflammation in experimental animals, but a similar role for DC in human allergic asthma has been difficult to define. This pilot study was undertaken to elucidate the role of DC in allergic asthma by examining their potential to migrate to the lower airways in response to bronchial challenge with specific allergen.

METHODS

Bronchial biopsy specimens were obtained from seven patients with allergic asthma before and 4-5 hours after allergen challenge. Multicolour immunofluorescence staining was performed on mucosal cryosections to identify changes in the number and phenotypes of DC.

RESULTS

A dramatic increase in the number of CD1c+HLA-DR+ DC were observed in the lamina propria after challenge compared with baseline (22.4 v 7.8 cells/mm(2)). The rapid accumulation (within 4-5 hours) of these cells strongly suggests that they were directly recruited from peripheral blood.

CONCLUSION

We have shown for the first time that a specific DC subset rapidly emigrates into the human bronchial mucosa during allergic inflammation. While this study is based on relatively few patients, the consistency of the overall results strongly suggests that the rapid population dynamics of human airway DC closely parallel those in animal models of acute inflammation. These findings support suggestions that DC have an important role in human airway allergy.

The impact of recent advances in immunology and cancer therapy on nuclear medicine

The explosive expansion of knowledge in immunology in recent decades has already affected the research and practice of nuclear medicine in several ways. New hematopoietic cells have been isolated and their functions discovered, including hematopoietic stem cells and dendritic cells (DCs). Many new humeral factors have been found that have potent effects on cells, including cytokines, growth factors, and specialized proteins. Radiolabeled compounds are needed to follow the pharmacodynamics of the humeral factors and to follow the migration of mobile cells in animals and humans. In this article, only DCs, cytokines, and growth factors used clinically are discussed. DCs are essential for defense against infectious diseases. Autologous DCs cultured for a week and pulsed with tumor antigens have already proved highly immunogenic compared with other methods for activating cytotoxic T cells, and preliminary studies suggest that DCs are more potent for tumor cell killing than monoclonal antibodies. DCs, unfortunately, also play an important role in causing certain human diseases. In allograft transplants, residual donor DCs are responsible for the cellular rejection; if they could be eliminated, rejection could be prevented. These cells are also detrimental in rheumatoid arthritis, other autoimmune diseases, asthma, and chronic obstructive pulmonary disease. Cytokines such as interleukin-2 and such growth factors as granulocyte-macrophage colony-stimulating factor and granulocyte colony-stimulating factor, administered to patients with malignancies to alleviate the leukopenia of chemotherapy agents, frequently alter the tissue distribution of radiopharmaceuticals; these alterations may be confused with disease.

Dendritic cells in the mucosa of the human trachea are not regularly found in the first year of life

BACKGROUND

Dendritic cells (DCs) in the mucosa of the respiratory tract might be involved in the early development of pulmonary allergy or tolerance. To date, little is known about when the first DCs occur in human airways.

METHODS

Specimens of the distal trachea from patients who had died from sudden death in the first year of life (n=29) and in older age groups (n=59) as well as from those who had died from respiratory tract infections in the first year of life (n=8) were examined by immunohistochemistry. Transmission electron microscopy was performed in additional samples from two adults.

RESULTS

In the sudden death subgroup DCs were absent in 76% of those who died in the first year of life but were present in 53 of the 59 older cases. All infants who had died of respiratory infectious diseases had DCs in the tracheal mucosa.

CONCLUSIONS

Mature DCs are not constitutively present in the human tracheobronchial mucosa in the first year of life, but their occurrence seems to be triggered by infectious stimuli. These data support the hypothesis that DCs play a crucial role in immunoregulation in early childhood.

Dendritic cells in the mucosa of the human trachea are not regularly found in the first year of life

BACKGROUND

Dendritic cells (DCs) in the mucosa of the respiratory tract might be involved in the early development of pulmonary allergy or tolerance. To date, little is known about when the first DCs occur in human airways.

METHODS

Specimens of the distal trachea from patients who had died from sudden death in the first year of life (n=29) and in older age groups (n=59) as well as from those who had died from respiratory tract infections in the first year of life (n=8) were examined by immunohistochemistry. Transmission electron microscopy was performed in additional samples from two adults.

RESULTS

In the sudden death subgroup DCs were absent in 76% of those who died in the first year of life but were present in 53 of the 59 older cases. All infants who had died of respiratory infectious diseases had DCs in the tracheal mucosa.

CONCLUSIONS

Mature DCs are not constitutively present in the human tracheobronchial mucosa in the first year of life, but their occurrence seems to be triggered by infectious stimuli. These data support the hypothesis that DCs play a crucial role in immunoregulation in early childhood.