Lung T cells in hypersensitivity pneumonitis

ATS/JRS/ALAT Hypersensitivity Pneumonitis Guidelines for Diagnosis of humidifier lung and summer-type hypersensitivity pneumonitis

BACKGROUND

The ATS/JRS/ALAT Guidelines for the Diagnosis of Hypersensitivity Pneumonitis (GL for HP) were published in 2020. Humidifier lung and summer-type HP are forms of HP, but it is unclear whether they can be diagnosed using GL for HP. This study examined the level of confidence where humidifier lung and summer-type HP can be diagnosed with GL for HP.

METHODS

Data from 23 patients with humidifier lung and 20 patients with summer-type HP (mean age, 67.3 and 57.4 years, respectively) diagnosed between October 2012 and January 2022 were retrospectively reviewed. We evaluated high resolution computed tomography (HRCT) patterns, bronchoalveolar lavage fluid (BALF) findings, exposures, and histopathological findings to determine the level of confidence where a diagnosis of HP could be made using the GL for HP.

RESULTS

HRCT pattern was classified as typical HP in 5 (22%) and compatible with HP in 18 (78%) patients with humidifier lung and considered as typical HP in 17 (85%) and compatible with HP in 3 (15%) patients with summer-type. The confidence level for diagnosis of HP was definite in 2 (8.7%), moderate in 14 (60.9%), and low in 7 (30.4%) patients with humidifier lung. It was definite in 12 (60%), high in 3 (15%), and moderate in 5 (25%) patients with summer-type HP.

CONCLUSIONS

GL for HP showed utility in diagnosing humidifier lung in many patients with a moderate to low confidence. However, there was a definite to high confidence for patients with summer-type HP.

Bronchoalveolar Lavage Lymphocytes in the Diagnosis of Hypersensitivity Pneumonitis among Patients with Interstitial Lung Disease

Rationale: Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) characterized by inflammation and/or fibrosis in response to an inhalational exposure.Objectives: To determine the value of bronchoalveolar lavage (BAL) fluid lymphocyte cellular analysis in the detection of HP among patients with newly detected ILD.Methods: This systematic review was undertaken in the context of development of an American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax clinical practice guideline. The clinical question was, "should patients with newly detected ILD undergo BAL fluid lymphocyte analysis to diagnose HP?" MEDLINE, EMBASE, and the gray literature were searched through October 2019. Studies that reported the percentage of BAL fluid lymphocytes for various ILDs were selected for inclusion. Meta-analyses compared the mean percentage of BAL fluid lymphocytes among patients with HP with that among patients with idiopathic pulmonary fibrosis (IPF) or sarcoidosis. The sensitivity and specificity by which various percentages of BAL fluid lymphocytes distinguish HP from IPF and sarcoidosis were also evaluated.Results: Eighty-four articles were selected. No randomized trials or observational studies were identified that compared BAL fluid lymphocyte analysis with no BAL fluid lymphocyte analysis in patients with ILD. Included studies were case series describing BAL fluid cell differentials in patients with various ILDs. The percentage of BAL fluid lymphocytes was significantly higher in both fibrotic and nonfibrotic HP compared with IPF. Similarly, the percentage of BAL fluid lymphocytes was significantly higher in both fibrotic and nonfibrotic HP compared with sarcoidosis. A threshold of 20% BAL fluid lymphocytes distinguished fibrotic HP from IPF with a sensitivity and specificity of 69% and 61%, respectively, and nonfibrotic HP from IPF with a sensitivity and specificity of 95% and 61%, respectively. It distinguished fibrotic HP from sarcoidosis with a sensitivity and specificity of 69% and 26%, respectively, and nonfibrotic HP from sarcoidosis with a sensitivity and specificity of 95% and 26%, respectively.Conclusions: The percentage of BAL fluid lymphocytes is higher in HP than IPF or sarcoidosis. However, a threshold that distinguishes HP from IPF or sarcoidosis with both high sensitivity and high specificity was not identified.

Ratiometric Semiconducting Polymer Nanoparticle for Reliable Photoacoustic Imaging of Pneumonia-Induced Vulnerable Atherosclerotic Plaque in Vivo

Acute pneumonia can greatly increase the vulnerable risk of atherosclerotic plaque and contribute to the mortality of cardiovascular disease. To accurately assess the rupture risk caused by acute pneumonia, we developed a novel kind of ratiometric semiconducting polymer nanoparticle (RSPN) for photoacoustic imaging of vulnerable plaque in apolipoprotein E-deficient mice complicated with pneumonia. Specifically, RSPN can react with O₂^•- and exhibit the enhanced photoacoustic signals at about 690 nm, while 800 nm is regarded as an internal photoacoustic reference. As a result, RSPN can provide reliable determination of O₂^•- within aortic atherosclerosis by analyzing the ratios of photoacoustic signals, which can successfully reflect the oxidative stress level in vulnerable plaque. Therefore, RSPN enable to specifically distinguish plaque-bearing mice and plaque-bearing mice complicated with pneumonia from healthy mice, which provides a promising tool to predict the vulnerability of plaque for reducing the mortality of atherosclerotic-induced cardiovascular disease.

Clinical and radiological characteristics of ultrasonic humidifier lung and summer-type hypersensitivity pneumonitis

BACKGROUND

Ultrasonic humidifier lung is a rare form of hypersensitivity pneumonitis (HP), and its clinical and radiological features are unclear. This study examined the clinical and radiological characteristics of humidifier lung.

METHODS

Data from 18 patients with humidifier lung (mean age, 67.3 years) diagnosed during October 2012 through April 2018 were retrospectively reviewed. We compared clinical, laboratory, and CT findings and bronchoalveolar lavage fluid (BALF) characteristics of these patients with those of 19 patients with summer-type HP (mean age, 57.4 years).

RESULTS

Cough and dyspnea were the most common symptoms. White blood cell count and serum C-reactive protein titers were higher for humidifier lung than for summer-type HP. Serum levels of Krebs von den Lungen-6 and surfactant protein D were significantly lower for humidifier lung than for summer-type HP. The most common chest CT findings in humidifier lung were ground-glass opacities (88.9%) and mosaic attenuation (50.0%). Centrilobular ground glass nodules were less common in humidifier lung than in summer-type HP (27.8% vs 63.1%; P = 0.043). Peribronchovascular or subpleural nonsegmental consolidation was more frequent in humidifier lung than in summer-type HP (44.4% vs 5.3%; P = 0.013). Lymphocyte fractions in BALF specimens were significantly lower for humidifier lung than for summer-type HP (37.3% vs 69.0%; P < 0.001). Neutrophil fractions were higher for humidifier lung, but the difference was not significant (22.1% vs 8.1%; P = 0.153). The CD4/8 ratio was higher for humidifier lung than for summer-type HP (1.7 vs 0.8; P = 0.003).

CONCLUSIONS

The clinical and radiological characteristics of humidifier lung differ from those of summer-type HP.

Diagnosis of Hypersensitivity Pneumonitis in Adults. An Official ATS/JRS/ALAT Clinical Practice Guideline

Background: This guideline addresses the diagnosis of hypersensitivity pneumonitis (HP). It represents a collaborative effort among the American Thoracic Society, Japanese Respiratory Society, and Asociación Latinoamericana del Tórax.Methods: Systematic reviews were performed for six questions. The evidence was discussed, and then recommendations were formulated by a multidisciplinary committee of experts in the field of interstitial lung disease and HP using the GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) approach.Results: The guideline committee defined HP, and clinical, radiographic, and pathological features were described. HP was classified into nonfibrotic and fibrotic phenotypes. There was limited evidence that was directly applicable to all questions. The need for a thorough history and a validated questionnaire to identify potential exposures was agreed on. Serum IgG testing against potential antigens associated with HP was suggested to identify potential exposures. For patients with nonfibrotic HP, a recommendation was made in favor of obtaining bronchoalveolar lavage (BAL) fluid for lymphocyte cellular analysis, and suggestions for transbronchial lung biopsy and surgical lung biopsy were also made. For patients with fibrotic HP, suggestions were made in favor of obtaining BAL for lymphocyte cellular analysis, transbronchial lung cryobiopsy, and surgical lung biopsy. Diagnostic criteria were established, and a diagnostic algorithm was created by expert consensus. Knowledge gaps were identified as future research directions.Conclusions: The guideline committee developed a systematic approach to the diagnosis of HP. The approach should be reevaluated as new evidence accumulates.

Bronchoalveolar lavage improves diagnostic accuracy in patients with diffuse lung disease

Bronchoalveolar lavage (BAL) is an established diagnostic tool in diffuse parenchyma lung disease. The objective of the present study was designed to investigate whether immunophenotyping affects BAL results and improves diagnostic accuracy. BAL from 61 patients was included in the study. The patients were also submitted to transbronchial biopsy, with a final diagnosis of granulomatous disease [tuberculosis (TB), n = 20; sarcoidosis (SARC), n = 3; and hypersensitivity pneumonitis (HP), n = 4]; idiopathic interstitial pneumonias (IIPs) [idiopathic pulmonary fibrosis (IPF), n = 9; organizing pneumonia (OP), n = 17]; and lung cancer (LC), n = 8. Immunohistochemistry and histomorphometry were used to identify and quantify type 1 and type 2 alveolar epithelial cells, macrophages, CD3+T-cells, CD4+T-cells, CD8+T-cells, and CD20+B-cells in BAL. These markers were correlated with a database and pulmonary function tests. The cellular, inflammatory, and immune components of BAL varied among the diagnostic groups and were negatively correlated with age and smoking history. An increased quantity of lymphocyte surface markers CD3 (P < 0.05) and CD20 (P = 0.01) was seen in IIPs. Patients with a pattern of OP had a higher proportion of type 2 alveolar epithelial cells; patients with SARC had a higher density of CD20+B-cells and CD4+T-helper cells; and patients with HP had a higher proportion of CD8+T-cytotoxic cells. A positive association was found between the density of type I alveolar epithelial cells and forced vital capacity. The immunophenotyping affects the cellular, inflammatory, or immune constituents of BAL and improved the diagnostic accuracy in diffuse parenchymal lung disease.

Role of alveolar epithelial early growth response-1 (Egr-1) in CD8+ T cell-mediated lung injury

Influenza infection of the distal airways results in severe lung injury, a considerable portion of which is immunopathologic and attributable to the host responses. We have used a mouse model to specifically investigate the role of antiviral CD8(+) T cells in this injury, and have found that the critical effector molecule is TNF-alpha expressed by the T cells upon antigen recognition. Interestingly, the immunopathology which ensues is characterized by significant accumulation of host inflammatory cells, recruited by chemokines expressed by the target alveolar epithelial cells. In this study we analyzed the mechanisms involved in the induction of epithelial chemokine expression triggered by antigen-specific CD8(+) T cell recognition, and demonstrate that the early growth response-1 (Egr-1) transcription factor is rapidly induced in epithelial cells, both in vitro and ex vivo, and that this is a critical regulator of a host of inflammatory chemokines. Genetic deficiency of Egr-1 significantly abrogates both the chemokine expression and the immunopathologic injury associated with T cell recognition, and it directly regulates transcriptional activity of a model CXC chemokine, MIP-2. We further demonstrate that Egr-1 induction is triggered by TNF-alpha-dependent ERK activation, and inhibition of this pathway ablates Egr-1 expression. These findings suggest that Egr-1 may represent an important target in mitigating the immunopathology of severe influenza infection.

Lung epithelial NF-kappaB and Stat1 signaling in response to CD8+ T cell antigen recognition

CD8+ T cell recognition of viral antigens presented by lung epithelial cells is important in the clearance of respiratory viral infection but may cause considerable injury to the lung. We have shown that a critical event of this type of injury is the activation of target epithelial cells and expression of chemokines by these cells. In this study, epithelial gene expression and transcription factor activation triggered by specific CD8+ T cell antigen recognition was examined in vitro and in vivo. T cell recognition triggers expression profiles of tumor necrosis factor-alpha (TNF-alpha)-dependent and interferon-gamma (IFN-gamma)-dependent genes in epithelial target cells. Consistent with these profiles, transcription factors nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1) were activated in lung epithelial cells of wild-type (WT) mice but not TNF receptor 1 (TNFR1)-deficient mice after CD8+ T cell recognition in vivo. In contrast, Stat1 activation and Stat1-dependent genes, such as IFN regulatory factor-1 (IRF-1) and guanylate-binding protein-2 (GBP-2), were induced to a similar extent in epithelial cells of both WT and TNFR1-deficient mice, indicating that this pathway is insufficient to induce pulmonary immunopathology in the absence of NF-kappaB-dependent transcriptional activation. Antibody neutralization of TNF-alpha abrogated epithelial monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) production in vitro as well as pulmonary immunopathology in vivo, confirming the primary importance of this cytokine in CD8+ T cell-mediated immunopathology.

CD4 T Lymphocyte–mediated Lung Disease

Although considerable evidence indicates a role for CD4(+) T lymphocytes (T cells) in airway inflammation, little data exist regarding the mechanisms underlying the induction and regulation of CD4(+) T cell reactivity to lung-specific antigens. To dissect the immunologic and molecular mechanisms of CD4(+) T cell dysregulation, reactivity to a self-antigen expressed in the lung of mice bearing a major histocompatibility complex class-II-restricted T cell receptor specific for this antigen was studied. Transgenic mice developed a progressive interstitial pneumonitis characterized by massive lymphocytic and plasmacytic infiltration of interalveolar septa, a clinical picture closely resembling some of the interstitial lung diseases. Pulmonary inflammation reached a plateau state in older mice with prominent formation of lymphoid follicles but reduced interstitial infiltration. Extensive immunologic characterization of self-reactive CD4(+) T cells isolated from the inflamed lung suggested the induction of regulatory T cells in the site of inflammation. Moreover, inflammation was accompanied by broad changes in the gene expression pattern toward a profile partially resembling that of activated, but strikingly, also that of regulatory CD4(+) T cells. Together our data provide important insights into functional and molecular alterations being associated with the induction and/or regulation of T cell-mediated pulmonary inflammation.

Toxic and other non-IgE-mediated effects of fungal exposures

There are more than 100000 recognized species of fungi, comprising 25% of the biomass of the earth. Allergic, IgE-induced, manifestations of airborne fungi are common, whereas non-IgE manifestations are rare. Recently, much focus has been placed on the non-IgE-mediated effects of various molds, including hypersensitivity pneumonitis, infectious disease, and mycotoxicoses. Hypersensitivity pneumonitis is a clinical syndrome associated with systemic and interstitial lung disease that occurs in susceptible individuals following fungal inhalation. Most fungi are not pathogenic to man; however, certain fungi are capable of infecting immunocompetent individuals. Although mycotoxins and exposure to mycotoxins ("toxic mold syndrome") are implicated in causing numerous, nonspecific, systemic symptoms, currently, there is no scientific evidence to support the allegation that human health is affected by inhaled mycotoxins. However, if mold is discovered in a home, school, or office setting, the source should be investigated and appropriate remediation undertaken to minimize structural damage and potential allergic sensitization.

[Hypersensitivity pneumonitis induced in guinea pigs by antigens to bat feces]

A bat feces extract was able to induce the synthesis of specific IgG in rabbits and IgE in atopics. These findings were corroborated by skin tests, RAST and RAST-inhibition. Nowadays, data concerning the experimental induction of hypersensitivity pneumonitis using a glycoprotein of bat feces are presented. This antigen was aerosolized for inhalation by adult guinea pigs for 12 weeks to detect specific serum IgM, IgG and IgE antibodies as well as sensitized T-CD4 cells. Histopathological studies of the lungs showed interstitial infiltrates of macrophages and lymphocytes, cellular bronchiolitis and single non-necrotizing granulomas from the seventh to the ninth weeks. From the tenth week to the end of the experiment the lesions of the lungs progressively worsened. The results from this animal model suggest that the chronic contact with the bat feces'antigen can induce other inflammatory lung reactions than those IgE dependant.

Indoor air quality and health does fungal contamination play a significant role?

Fungal contamination in buildings can vary greatly, and their presence in a dwelling does not necessarily constitute exposure. Measurement of mold spores and fragments varies depending on the methodology and instruments used. Meaningful comparison of data is rarely possible. The presence of a specific immune response to a fungal antigen only connotes that exposure to one or more related species has occurred, but not that there is a symptomatic clinical state. The response of individuals to indoor bioaerosols is complex and depends on age, gender, state of health, genetic makeup, and degree and time of bioaerosol exposure. In general, mold contamination in buildings is associated with incursion of water or moisture, which should be remedied as efficiently as possible. When disease occurs, it more likely is related to transient annoyance or irritational reactions. Allergic symptoms may be related to mold proliferation in the home environment. Because molds are encountered both indoors and outdoors, it is difficult to determine where the sensitivity initially arose and if the response is solely provoked by either an indoor or outdoor source. As an indoor allergen, mold is considered to be an infrequent participant in the induction of allergic disease when compared with housedust mites, animal dander, and cockroach allergens. Infection in healthy individuals is rare and usually is caused by an outdoor source. Building-related disease caused by mycotoxicosis has not been proved in the medical literature.

Agricultural lung disease

Agricultural work is associated with high rates of injury, disability, and illness. Agricultural workers are at increased risk for a variety of illnesses including respiratory disorders, dermatologic conditions, and cancer. The recognition of ODTS led to increased understanding of acute illness in farmers and grain workers. Previously, many cases of acute illness were probably erroneously called farmer's lung. The same agents that are responsible for ODTS are responsible for the high prevalence of bronchitis in certain agricultural workers. The recent description of the innate immune system is very exciting because it will lead to increased understanding of the pathogenesis of organic dust induced disorders.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is a group of immunologically mediated lung diseases caused by the inhalation of environmental agents in susceptible individuals. Most HP patients are non-smokers and have been exposed to organic dusts from vegetable or animal products. Some HP cases are associated with exposures to relatively simple chemical compounds. HP may present as an acute, subacute, or chronic disease and may follow various clinical courses. The type of exposure is thought to be more important in the clinical outcome than the nature of the antigen. A diagnosis of HP is often considered on the basis of clinical history of exposure with resulting respiratory symptoms, but the definitive diagnosis requires a constellation of clinical, radiologic, laboratory, and pathologic findings. The characteristic histologic triad in HP includes bronchiolitis, interstitial lymphocytic infiltration, and granulomas; however, biopsy in HP cases may lack the diagnostic triad and manifest as nonspecific interstitial pneumonia (NSIP). Avoiding exposure to the offending antigen(s) is usually sufficient to resolve symptoms and physiological abnormalities. Pulmonary fibrosis and physiological abnormalities occurring in chronic HP may be irreversible. Steroid therapy is helpful for symptomatic relief, but probably does not affect the long-term prognosis. Type III and type IV hypersensitivity reactions are involved in the pathogenesis; alveolar macrophages and T cells (Th-1 type) play a central role in the immune responses after antigen exposure via their increased interaction and secretion of regulatory mediators.

Hypersensitivity pneumonitis induced by spores of Lyophyllum aggregatum

OBJECTIVES

Lyophyllum aggregatum (LA) is called Shimeji in Japanese and is eaten commonly as a mushroom. Shimeji mushrooms are cultivated in an indoor environment all year round. This study aimed to clarify the clinical features of hypersensitivity pneumonitis (HP) induced by LA.

PATIENTS AND SETTING

Ten patients showed mild respiratory symptoms including dry cough, sputum, and low-grade fever. We tried to characterize the clinical features and the findings using chest high-resolution CT (HRCT), pulmonary function tests (PFTs), and BAL fluid (BALF) tests in patients with HP induced by LA. HP was diagnosed from clinical features, HRCT findings, BALF findings, lung histology, and lymphocyte stimulation tests (LSTs) for LA.

RESULTS

Laboratory findings showed mean (+/- SD) elevated levels of C-reactive protein (0.78 +/- 1.3 mg/dL), erythrocyte sedimentation rate (48 +/- 23 mm/h), and gamma-globulin (26.9 +/- 7.6%). PFTs revealed a slight decrease in the percentage diffusing capacity of the lung for carbon monoxide, possibly due to the presence of epithelial granulomas in the alveoli. Although 4 of 10 patients showed normal findings on the chest radiograph (CXR), chest HRCT findings of all patients showed centrilobular small nodules and diffuse ground-glass opacities. The BALF testing revealed an increase in total cell counts, showing predominantly activated T lymphocytes. The CD4/CD8 cell ratio was significantly decreased (0.5 +/- 0.3). The results of the LSTs were positive in seven of seven cases.

CONCLUSIONS

Since patients with HP induced by LA typically have mild respiratory symptoms and sometimes normal CXR findings, their conditions might remain undiagnosed. However, the chest HRCT images showed the typical subacute phase of HP.

Tumor necrosis factor-alpha -308 promoter gene polymorphism and increased tumor necrosis factor serum bioactivity in farmer's lung patients

Hypersensitivity pneumonitis (HP) represents an immunologic reaction of the pulmonary parenchyma to an inhaled agent. Since tumor necrosis factor (TNF)-alpha is thought to be involved in the pathogenesis of HP, and polymorphisms in the TNF genes have been associated with variations in the production of TNF-alpha, we investigated the serum bioactivity and genotype of TNF in HP. TNF bioactivity was measured after hay dust challenge in eight patients with farmer's lung (Group A) and in 12 healthy, sensitized (antibody-positive) controls (Group B). Genotyping for the -308 TNF-alpha promoter polymorphism and the TNF-beta intron 1 gene polymorphism was performed in 20 patients with farmer's lung, 25 patients with pigeon breeder's lung, and 216 controls. TNF bioactivity increased in Group A at 4 to 10 h after hay dust challenge, but not in Group B (p < 0.05). The frequency for the TNFA2 allele, a genotype associated with high TNF-alpha production in vitro, was significantly higher in farmer's lung patients (frequency [f] = 0.43, p = 0.0012) than in controls (f = 0.19) or patients with pigeon breeder's lung (f = 0.16). Genotyping for TNF-beta revealed no significant abnormalities. Thus, increased production of TNF-alpha after hay contact, and a genetic predisposition to TNF-alpha production, are implicated in the pathogenesis of alveolitis in farmer's lung.

Alveolar epithelial cell chemokine expression triggered by antigen-specific cytolytic CD8(+) T cell recognition

CD8(+) T lymphocyte responses are a critical arm of the immune response to respiratory virus infection and may play a role in the pathogenesis of interstitial lung disease. We have shown that CD8(+) T cells induce significant lung injury in the absence of virus infection by adoptive transfer into mice with alveolar expression of a viral transgene. The injury is characterized by the parenchymal infiltration of host cells, primarily macrophages, which correlates with physiologic deficits in transgenic animals. CD8(+) T cell-mediated lung injury can occur in the absence of perforin and Fas expression as long as TNF-alpha is available. Here, we show that the effect of TNF-alpha expressed by CD8(+) T cells is mediated not exclusively by cytotoxicity, but also through the activation of alveolar target cells and their expression of inflammatory mediators. CD8(+) T cell recognition of alveolar cells in vitro triggered monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-2 (MIP-2) expression in the targets, which was mediated by TNF-alpha. Antigen-dependent alveolar MCP-1 expression was observed in vivo as early as 3 hours after CD8(+) T cell transfer and depended upon TNF-R1 expression in transgenic recipients. MCP-1 neutralization significantly reduced parenchymal infiltration after T cell transfer. We conclude that alveolar epithelial cells actively participate in the inflammation and lung injury associated with CD8(+) T cell recognition of alveolar antigens.

B-lymphocyte aggregates in alveoli from a child with hypersensitivity pneumonitis (bird breeders lung)

BACKGROUND

Hypersensitivity pneumonitis is an interstitial lung disease mediated through a patient's immunologic response to a variety of inhaled organic dusts. Studies of the cellular components of lavage fluid from patients with this disease show marked increases of CD8+ suppressor/cytotoxic T-lymphocytes.

OBJECTIVE

In this study, we identified, in addition to the expected suppressor T-cells and natural killer cells, follicle-like aggregates of B-cells in the lung interstitium of an affected patient.

METHODS

The patient was an 11-year-old non-asthmatic, Caucasian male who presented with a 4-month history of progressive dyspnea, cough, and fever. The home contained nine cockatiel and two doves. Admission pulmonary functions revealed a restrictive pattern with diminished diffusion capacity. Prior to a diagnosis, the patient underwent bronchoalveolar lavage and transbronchial biopsy. Serum precipitins were eventually positive to pigeon (which cross-reacts with dove) droppings. The symptoms resolved after a prolonged course of prednisone.

RESULTS

Analysis of bronchoalveolar lavage lymphocyte population revealed a predominance of CD8+ cells (50%) with 85% expressing the activation marker HLA-DR. The percentage of CD4+ and CD56+ were 32% and 16%, respectively. The transbronchial biopsy revealed CD20+ follicle-like aggregates within the lung interstitium.

CONCLUSIONS

The histopathologic findings confirm that in hypersensitivity pneumonitis, the predominant immune response is an infiltrate of CD8+ T cells. The presence of B cell aggregates, however, may indicate that the local synthesis of antibody may be involved in an antibody-dependent cellular cytotoxic mechanism.

Polarized Type 1 Cytokine Profile in Bronchoalveolar Lavage T Cells of Patients with Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is characterized by an inflammatory lymphocytic alveolitis comprised of both CD8+ and CD4+ T cells. Animal models suggest that HP is facilitated by overproduction of IFN-γ, and that IL-10 ameliorates severity of the disease, indicating a Th1-type response. To determine whether a Th1 phenotype in HP also exists clinically, bronchoalveolar lavage (BAL) and peripheral blood (PB) T cells were obtained from HP individuals and analyzed for Th1 vs Th2 cytokine profiles. It was determined that soluble OKT3-stimulated BAL T cells cocultured with alveolar macrophages produced more IFN-γ and less IL-10 than PB T cells cocultured with monocytes, but no difference was observed in IL-4 production. The monocytic cells did not account for this difference, as CD80 and CD86 expressions were similar, and coculturing PB T cells with alveolar macrophages resulted in no difference in IFN-γ production. Similarly, there was no difference in IL-12 production between stimulated BAL or PB T cells; however, addition of rIL-12 significantly increased production of IFN-γ by BAL T cells, but not by PB T cells. This effect was due to a difference in IL-12R expression. High affinity IL-12R were only present in association with BAL T cells. These studies indicate that clinical HP is characterized by a predominance of IFN-γ-producing T cells, perhaps resulting from a reduction in IL-10 production and an increase in high affinity IL-12R compared with blood T cells.

Perforin-independent CD8(+) T-cell-mediated cytotoxicity of alveolar epithelial cells is preferentially mediated by tumor necrosis factor-alpha: relative insensitivity to Fas ligand

CD8(+) T cells appear to play an important pathophysiologic role in many inflammatory lung diseases. The primary effector function of this T-cell subset is cytolysis of virus-infected cells, and it is widely believed that there are two primary molecular mechanisms by which this occurs: the perforin/granzyme-mediated pathway of cytolysis, and the Fas ligand (FasL)-Fas (CD95/APO-1) pathway of induction of target-cell apoptosis. This conclusion is based primarily on data obtained with hematopoetic cell lines as target cells. There is also a growing body of evidence that Fas is involved in the transduction of apoptotic signals in a variety of inflammatory disease states, particularly involving the liver and the lung. In the study reported here we took advantage of a novel in vitro assay to directly assess the effector mechanisms employed in CD8(+) T-cell-mediated cytolysis of alveolar epithelial cells. We present evidence that FasL-induced, Fas-mediated apoptosis does not directly contribute to T-cell-mediated cytolysis of alveolar epithelial-derived cells, even though Fas is expressed and functional on these cells. We also demonstrated that the perforin-independent cytolytic activity of CD8(+) T cells against alveolar epithelial-derived cells is explained entirely by tumor necrosis factor-alpha (TNF-alpha), which is expressed on CD8(+) T cells. Furthermore, we show that bystander cytolysis of alveolar epithelial-derived cells by antiviral CD8(+) T cells is entirely perforin-independent. This activity is mediated exclusively by TNF-alpha. Both alveolar epithelial-derived cells and primary murine type II cells show susceptibility to apoptosis triggered by soluble TNF-alpha, without the need for transcriptional or translational inhibition. We also confirmed the resistance of alveolar type II cells to FasL in vivo by performing adoptive transfer of perforin-deficient antiviral CD8(+) T cells into transgenic mice expressing a target antigen in type II epithelial cells. Significant lung injury developed in the transgenic CD8(+) T-cell recipients, whether or not Fas was expressed in these animals. Furthermore, preincubation of the T cells with antibody to TNF-alpha completely abolished the injury. These results suggest that alveolar epithelial cells are relatively sensitive to T cell-triggered, TNF-alpha-mediated apoptosis, and resistant to apoptosis triggered by FasL. These observations may have important ramifications for understanding of the pathophysiology of interstitial and inflammatory lung diseases.

Structural and functional consequences of alveolar cell recognition by CD8(+) T lymphocytes in experimental lung disease

CD8(+) T cells infiltrate the lung in many clinical conditions, particularly in interstitial lung disease. The role(s) that CD8(+) T cells might be playing in the pathogenesis of inflammatory lung disease is unclear at present, as is the direct contribution of CD8(+) T cell effector activities to lung injury. This report describes a transgenic model used to evaluate the impact, on respiratory structure and function, of CD8(+) T lymphocyte recognition of a target antigen expressed endogenously in alveolar epithelial cells. We found that adoptive transfer of cloned CD8(+) cytotoxic T lymphocytes (CTLs) specific for an alveolar neo-antigen (influenza hemagglutinin) leads to progressive lethal injury in transgenic mice, which dramatically affects lung structure and function. Transgenic recipients of CD8(+) CTLs exhibited tachypnea and progressive weight loss, becoming moribund over a period of several days. Concomitantly, the animals developed a progressive interstitial pneumonitis characterized initially by lymphocytic infiltration of alveolar walls and spaces, followed by an exuberant mononuclear cell infiltration that correlated with restrictive pulmonary mechanics and a progressive diffusion impairment. These results indicate that antigen-specific CD8(+) T cell recognition of an alveolar epithelial "autoantigen" is, in and of itself, sufficient to trigger an inflammatory cascade that results in the histological and physiological manifestations of interstitial pneumonia.

Comparison of histamine-releasing factor recovered from skin and peripheral blood mononuclear cells of patients with chronic idiopathic urticaria

BACKGROUND

The pathogenesis of chronic idiopathic urticaria is characterized by defective histamine release. Skin mast cells show an increased release of histamine while circulating basophils are less responsive to immunologic stimulus.

OBJECTIVE

The purpose of the study was to examine and compare the production of the histamine-releasing factor in the skin and within the peripheral blood of patients with chronic idiopathic urticaria and normal control subjects, as a possible factor responsible for the difference observed in the releasability of both skin mast cells and basophils.

METHODS

Using the skin chamber technique, histamine-releasing factor production and histamine concentration were assessed in normal-appearing skin of patients with chronic idiopathic urticaria (n = 12) and normal controls (n = 5) over a 2-hour observation period. In both groups, histamine-releasing factor production by peripheral blood mononuclear cells was also measured.

RESULTS

The weighted average of histamine-releasing factor production during the 2-hour observation period was higher in the non-lesional skin of patients with chronic idiopathic urticaria as compared with normal controls (5.6 +/- 1.4% versus 0.7 +/- 0.6%, P < .01). In contrast, less histamine-releasing factor was produced by peripheral blood mononuclear cells in chronic urticaria as opposed to normal controls (17.2 +/- 2.1% versus 25.7 +/- 2.8%, P < .03). Spontaneous histamine concentration was not significantly different in patients with chronic urticaria than in normal controls.

CONCLUSION

Histamine-releasing factor production is increased in the skin, and decreased in the peripheral blood of patients with chronic idiopathic urticaria when compared with nonatopic controls. The lower production of histamine releasing factor in the blood could be explained by the migration of activated T-lymphocytes in the skin.

Lung lymphocytes: origin, biological functions, and laboratory techniques for their study in immune-mediated pulmonary disorders

Different types of immunocompetent cells, including T lymphocytes and alveolar macrophages, account for pulmonary host defense. Taking advantage of the availability of the monoclonal antibody technique, cell culture facilities, pure recombinant cytokines, and molecular probes for their genes, in the last few years it has been possible to keenly study the different steps that lead to the compartmentalization of immune response in human lung. Furthermore, the immunological analysis of cells retrieved from bronchoalveolar lavage (BAL) allowed recognition of the importance of immune mechanisms in the evolution of immune-mediated pulmonary disorders. The purpose of this review is to summarize recent advances on the immunologic characterization of lung lymphocytes in health and disease. Following a brief description of the pathways through which the pulmonary lymphoid system contributes to removing potentially harmful inhaled antigenic materials, available laboratory techniques to evaluate the lymphoid component of the pulmonary immune system and their byproducts are discussed. These techniques cover methods for preparing lymphocytes from the BAL fluid and for characterizing lung lymphocytes both in cell suspensions and pulmonary tissue biopsies. Other sections of this review describe the techniques for measuring the immunologic effector functions of lung lymphocytes. We also provide the reader with a flavor of the molecular biology methods used to characterize lymphocytes in the pulmonary microenvironment. The final sections of the review article highlight the pathogenetic role envisaged for lymphoid cells in pulmonary disease states and emphasize the importance of the BAL analysis in the clinical management of the most relevant immune-mediated lung disease.

Antioxidant therapy partially blocks immune-induced lung fibrosis

A mouse model of hypersensitivity pneumonitis was generated by challenge with a thermophilic actinomycete. Oxygen radical scavengers were administered to challenged mice: vitamin E at 1000 units daily, polyethylene glycol-superoxide dismutase (SOD) at 500 units daily, polyethylene glycol-catalase at 10,000 units daily, 1,3,dimethyl-2-thiourea (DMTU) at 2 mg daily, and the biomimetic SOD, copper(II) [diisopropyl salicylate]2 (CuDIPS) at 1 mg daily. At three weeks after actinomycete challenge, a 10-fold increase in bronchoalveolar (BAL) cell number was observed. Treatments with catalase or DMTU were without effect on the BAL cell number in challenged mice. However, infusion of vitamin E was associated with an increased BAL cell influx (15-fold increase at two and three weeks). Similarly, treatment with PEG-SOD and CuDIPS resulted in an increase in cell number at two and three weeks. PEG-SOD or CuDIPS treatment resulted in a strong neutrophilia, whereas control challenged mice had a cellular influx mostly of macrophages and lymphocytes. Vitamin E treatment of challenged mice led to an increased T lymphocyte recruitment at two and three weeks. In vitro studies showed that actinomycete challenge was associated with an enhancement of alveolar macrophage O2- release, which was blocked by PEG-SOD, vitamin E, or DSC treatment but was unaffected by catalase or DMTU treatment. In control challenged mice, there was a 25-fold increase in the BAL albumin concentration at two weeks. PEG-SOD, vitamin E, or CuDIPS treatment all decreased the albumin concentration; the three modulators also diminished lung fibrosis at two or three weeks, as seen by a decrease in lung hydroxyproline and collagen synthesis by lung fibroblasts. Examination of sections from lungs of challenged animals showed evidence of cellular infiltrates around the bronchi and the blood vessels. Challenged mice given continuous infusions of vitamin E, SOD, or CuDIPS had lung histological scores that were significantly lower than control challenged mice or challenged mice treated with catalase or DMTU. Thus, therapies based on O2- scavenging or treatment with a general antioxidant such as vitamin E may hold some promise in the treatment of hypersensitivity pneumonitis.

Hypersensitivity pneumonitis associated with home ultrasonic humidifiers

We describe five patients with hypersensitivity pneumonitis (HP) that was related to using home ultrasonic humidifiers. All patients had micronodular infiltrates on their chest radiograph, and their lung biopsy specimens revealed alveolitis with or without epithelioid cell granulomas. Challenge tests were performed on two patients with the humidifier water and three patients using the humidifier. All patients tested exhibited a positive response. Tests for precipitating antibodies against an extract of the humidifier water gave strongly positive reactions in all patients tested. Precipitins to Cephalosporium acremonium and Candida albicans were also present in all cases, whereas precipitins to thermophilic actinomycetes were not detected. Although cultures of the water grew a variety of fungal and bacterial organisms, thermophilic actinomycetes could not be detected. These findings suggest that thermophilic organisms may not be the causative antigens of HP associated with ultrasonic humidifiers. All five patients had an increase in the bronchoalveolar lavage (BAL) lymphocytes that were predominantly CD4+ lymphocytes. The T helper cell count (CD4) to suppressor T cell count (CD8) ratio was significantly higher than that observed in summer-type HP, and lower than that observed in bird fancier's lung, indicating that the phenotypes of the BAL lymphocytes may vary with the type of HP.

Radiation and the lung: a reevaluation of the mechanisms mediating pulmonary injury

Recent data from several investigators, including our unit, have provided additional information on the etiology of radiation-induced lung damage. These data suggest that there are two quite separate and distinct mechanisms involved: (a) classical radiation pneumonitis, which ultimately leads to pulmonary fibrosis is primarily due to radiation-induced local cytokine production confined to the field of irradiation; and (b) sporadic radiation pneumonitis, which is an immunologically mediated process resulting in a bilateral lymphocytic alveolitis that results in an "out-of-field" response to localized pulmonary irradiation. Both animal experiments and human studies show that classical radiation pneumonitis has a threshold dose and a narrow sigmoid dose-response curve with increasing morbidity and mortality over a very small dose range. Clinical pneumonitis rarely causes death, whereas in the animal and human studies of classical radiation pneumonitis, all subjects will eventually suffer irreversible pulmonary damage and death. The description of classical radiation pneumonitis is that of an acute inflammatory response to lung irradiation, which is confined to the area of irradiation. Recent studies have also shown that irradiation induces gene transcription and results in the induction and release of proinflammatory cytokines and fibroblast mitogens in a similar fashion to other chronic inflammatory states, and which ultimately results in pulmonary fibrosis. The description of classical radiation pneumonitis does not adequately explain the following observed clinical characteristics: (a) the unpredictable and sporadic onset; (b) the occurrence in only a minority of patients; (c) the dyspnoea experienced, which is out of proportion to the volume of lung irradiated; and (d) the resolution of symptoms without sequelae in the majority of patients. We have demonstrated a bilateral lymphocytic alveolitis of activated T lymphocytes and a diffuse increase in gallium lung scan uptake in patients studied before and 4 to 6 weeks after strictly unilateral lung irradiation. This is suggestive of a hypersensitivity pneumonitis, which gives rise to an "out-of-field" response to localized lung irradiation and hence more accurately describes the clinical picture of radiation pneumonitis. Reevaluation of the mechanisms of pulmonary injury from irradiation suggest that (a) a new term, sporadic radiation pneumonitis, should be introduced to describe the clinical picture of radiation pneumonitis, which is not adequately explained by the classical description and is quite clearly an entirely different process; and (b) that the chronic response to localized lung irradiation that leads to pulmonary fibrosis is largely mediated through the induction and release of tissues cytokines.

Sawdust-induced inflammatory changes in rat lung: effects on alveolar and interstitial cells in relation to time

Exposure to sawdust and its contaminants, e.g., terpenes, may cause respiratory tract and lung parenchymal inflammation. To monitor these changes over time. Sprague-Dawley rats were exposed at one occasion to 2.5 mg sawdust or saline by intratracheal instillation. Flow cytometry analyses were done on bronchoalveolar lavage (BAL) cells. Lung tissue specimens were analyzed histologically and immunohistochemically. After one week, the number of BAL polymorphonuclear leukocytes was increased (P < 0.05, N = 8), followed at six weeks by increases of macrophages and lymphocytes (both P < 0.01, N = 8). Enhanced expressions of class II antigens and complement receptors on macrophages after one week were even more pronounced at six weeks, indicating cellular activation. The BAL findings, also including increased (P < 0.001, N = 8) concentrations of hyaluronan with progressing changes over time, confirmed the signs of inflammation, as did the histological analysis of the lung tissue specimens with an accumulation of polymorphonuclears, macrophages, and hyaluronan in the interstitium.

Mast cell and histamine involvement in farmer's lung disease

The aim of this study was to evaluate the cellular and biochemical characteristics of the bronchoalveolar lavage (BAL) fluid in patients with farmer's lung disease (FLD). Total cell numbers in BAL fluids from patients with FLD (n = 30) were significantly higher than in normal subjects (n = 7; p < 0.01), and differential cell counts were significantly different. Lymphocytes were the most numerous cell type in BAL fluids from patients with FLD (65.4 +/- 2.5 percent vs 6.8 +/- 0.5 percent), and analysis of lymphocyte subsets revealed increased percentages of CD3+ and CD8+ cells (91.8 +/- 0.9 percent vs 68.8 +/- 3 percent, p < 0.01, and 54.3 +/- 3.1 percent vs 30.1 +/- 3.2 percent, p < 0.01, respectively). A marked increase in mast cell numbers, as revealed by the specific alcian blue/safranin staining, was observed in patients with FLD (4.2 +/- 0.57 percent, n = 12, vs 0.18 +/- 0.04 percent, n = 7, p < 0.001). Histamine levels in BAL supernatants were increased in patients with FLD (mean = SEM, 4.4 +/- 0.8 ng/ml vs 0.9 +/- 0.1 ng/ml; median, 2.4 ng/ml vs 0.9 ng/ml, p < 0.01), and correlated positively with mast cell numbers and percentages (r = +0.63, p < 0.03, and r = +0.69, p < 0.02, respectively); conversely, a negative correlation was found between histamine levels and CD8+ lymphocyte percentages (r = -0.48, p < 0.01). Raised neutrophil percentages (5.1 +/- 0.8 vs 0.5 +/- 0.18, p < 0.05) and albumin concentrations (29.2 +/- 3.9 mg/dl vs 3.4 +/- 1.3 mg/dl, p < 0.01) were also found in patients with FLD. These findings show that increased numbers of mast cells, lymphocytes, and neutrophils can be found in BAL fluids of patients with FLD. The increased histamine levels in the supernatants of BAL fluids indicate that mast cells are activated. These data allow us to postulate a role for mast cell accumulation and histamine release in the inflammatory process of FLD.

Experimental hypersensitivity pneumonitis in mice induced by Trichosporon cutaneum: histologic and immunologic features and effect of in vivo depletion of T cell subsets

An animal model of hypersensitivity pneumonitis (HP) was developed in C57Black/6J mice by repeated intratracheal inoculations with particulate Trichosporon cutaneum, a causative agent of Japanese summer-type HP. We observed severe alveolitis and bronchiolitis with infiltration of lymphocytes, macrophages, and neutrophils in the lung lesions. Granuloma formation was occasionally seen. Bronchoalveolar lavage (BAL) of the experimental animals showed an increase in the number of lymphocytes, macrophages, neutrophils, and in the total cell yield. Phenotypic analysis of the BAL lymphocytes by flow cytometry revealed that 43.1 +/- 3.1% of lymphocytes were Thy1.2+ (CD3+) cells and that the L3T4+ (CD4+) cells (36.3 +/- 3.5%) predominated over the Lyt2+ (CD8+) cells (18.5 +/- 1.2%). As for the humoral immune response, the specific IgA antibody activities in the BAL fluids well reflected the specific pulmonary inflammatory responses. Studies of lymphocyte depletion were performed by in vivo administration of anti-CD4 and anti-CD8 monoclonal antibodies. Depletions of CD4+ cells and of both CD4+ and CD8+ cells diminished the pulmonary lesions and specific IgA antibody activities in the BAL fluids. These results indicate that CD4+ cells may play a major role in the inflammatory process of this animal model.

Pulmonary lymphocyte recruitment: depletion of CD8+ T cells does not impair the pulmonary immune response to intratracheal antigen

CD8+ T cells predominate in the lungs in hypersensitivity and human immunodeficiency virus-related lymphocytic pneumonitis, but their role in the immunopathogenesis of lung disease is unknown. We have shown that in immunized mice depleted of CD4+ T cells, CD8+ T cells are recruited into the lungs in response to intratracheal antigen challenge with sheep red blood cells (SRBC) (J. Clin. Invest. 1991; 88:1244-1254) or to pulmonary infection with Pneumocystis carinii (Am. J. Respir. Cell Mol. Biol. 1991; 5:186-197), suggesting that recruitment of CD8+ T cells does not depend on CD4+ T cell-derived signals. Because CD8+ T cells themselves produce a variety of chemotactic and immunoregulatory cytokines, CD8+ T cells may be important participants in, and modulators of, pulmonary immune responses. To test this hypothesis, we examined the effects of CD8+ T cell depletion on the generation of a pulmonary immune response in vivo. We monitored the recruitment of mononuclear cells into lungs in the absence of CD8-dependent signals and measured the duration of pulmonary inflammation in the absence of suppressor CD8+ T cells. Primed mice were treated with anti-CD8 monoclonal antibody to deplete CD8+ T cells and subsequently were challenged intratracheally with 5 x 10(8) SRBC. At various times after challenge, total and differential cell counts and lymphocyte phenotypes were measured in bronchoalveolar lavage fluid by flow cytometry and lungs were scored histologically. We found that depletion of CD8+ T cells neither decreased recruitment of immune and inflammatory cells nor prolonged the pulmonary immune response.(ABSTRACT TRUNCATED AT 250 WORDS)

Flexible bronchoscopy as a diagnostic tool in the evaluation of pulmonary tuberculosis in an elderly population

OBJECTIVE

This study intends to determine what role fiberoptic bronchoscopy (FOB) plays in the diagnosis of tuberculosis (TB), particularly in a geriatric population.

DESIGN

Cases of tuberculosis reported to the Tennessee Department of Health during the years 1989 and 1990 were divided into two age groups: Group A (< 65 years) and Group B (> or = 65 years). Natural sputum smears and cultures positive for M. tuberculosis (M. TB) in each group were compared with FOB specimens, acid-fast bacilli (AFB) smears and cultures. Data were analyzed by chi-square tests of independence for each year, then compared to determine statistical significance.

SETTING AND PATIENTS

Of the 601 TB cases reported to the State of Tennessee in 1989, 285 patients were in Group A and 316 in Group B. For 1990, 525 cases were reported, 269 in Group A and 256 in Group B. All cases met CDC-approved criteria for diagnosis of tuberculosis.

MEASUREMENTS

The number of positive AFB smears and M. TB cultures were compared in each group. In cases with sputum negative but FOB specimens positive for TB, identification was made by FOB only.

MAIN RESULTS

In Group A, 26 (9.1%) were diagnosed by FOB; only eight of these had positive sputum cultures. In Group B, 77 (24.4%) were diagnosed by FOB. Of these, 23 had positive sputum cultures; the remaining 54 patients (17.1%) had diagnoses based on FOB alone. In 1990, 269 cases of TB were reported in Group A. Of these, 38 (14.1%) were diagnosed by FOB. There were 256 TB cases reported among Group B, 83 (32.4%) of which were diagnosed by FOB. Of these 83 cases, 60 (23.4%) were diagnosed by FOB only. While no statistically significant difference was seen between the 1989 and 1990 rates of TB diagnosis by FOB for those in Group A (age < 65), the difference in rates for those in Group B (age > or = 65) was statistically significant (P < 0.05).

CONCLUSIONS

A steady increase in the use of FOB as a diagnostic tool was noted, suggesting that a significant number (19.9%) of geriatric TB cases might have been missed without the aid of FOB. While the exact reason for its increased utilization is not known, this study indicates that FOB has become a more important source of diagnosis in pulmonary TB, particularly among the elderly.

A study of monokine release and natural killer activity in the bronchoalveolar lavage of subjects with farmer's lung

We examined the interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha) releasability of alveolar macrophages and the natural killer (NK) cell activity in the bronchoalveolar lavage (BAL) cells of 11 patients with Farmer's lung at different stages of the disease. Although there were some variations in the levels of monokine release, macrophages of patients with acute disease secreted significantly higher spontaneous levels of TNF alpha than did a nonfarming control group (p = 0.0002). Conversely, TNF alpha release stimulated by bacterial lipopolysaccharide (LPS) was similar in patients with acute disease when compared with that in normal control subjects. IL-1 was also spontaneously secreted in significantly greater amounts by patients with acute Farmer's lung than by subjects in a control group (p = 0.0001). However, LPS-induced IL-1 release was significantly diminished in BAL macrophages from patients with acute manifestations of the disease when compared with that in control subjects (p = 0.001). Treating hypersensitivity pneumonitis with corticosteroids or by contact avoidance resulted in very significant decrease in spontaneous and LPS-stimulated IL-1 production by BAL macrophages (p = 0.0001 and p = 0.03, respectively), as well as in a decrease in spontaneous TNF alpha release that was also significant (p = 0.01). In addition, BAL cells of patients in the acute phase had a significant NK cell activity (mean +/- SEM of 18.33 +/- 2.65%). Treatment of these patients resulted in an increase in NK cell activity (mean of 40.17 +/- 7.86%), which was significantly different from values of patients with acute disease (p = 0.037).(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular and cytokine profiles in spontaneous regression phase of hypersensitivity pneumonitis

The phase of spontaneous regression of hypersensitivity pneumonitis was evaluated using a mouse model. C57BL/6 mice were instilled intranasally with 150 micrograms of the thermophilic actinomycete Faeni rectivirgula 3 days a week so as to establish a mouse model of farmer's lungs. It was shown that instillation of mice for a period of more than 6 weeks was associated with a significant decrease in the lung inflammation, suggestive of the so-called spontaneous regression phase seen in this pathology. Indeed, the lung index was seen to decrease after more than 6 weeks of treatment (2.2 after 6 weeks vs. 1.7 at 12 weeks, p < .01). There was also a significant decrease in lung hydroxyproline levels in animals given 12 weeks of treatment (175 micrograms/lung) compared to 6-week-treated animals (212 micrograms/lung, p < .05). Treated mice did not show a significant decrease in the alveolitis after 9 weeks of treatment. Also, there was no evidence that there was a decrease in bronchoalveolar lavage macrophage or T lymphocyte activity in mice given more than 9 weeks of F. rectivirgula treatment, as judged by O2- release and antigen-driven proliferation. Conversely, it was shown that NK cell activity in the lung digest of mice given 9 to 12 weeks of instillation was significantly higher than that seen in mice given 6 weeks of treatment. Analysis of the lung cell cytokine profile seen after ConA mitogenesis showed that after 6 weeks of F. rectivirgula treatments, nonparenchymal cells secreted high levels of tumor necrosis factor alpha (TNF alpha) and granulocyte macrophage colony-stimulating-factor (GM-CSF), whereas similar cells from the lungs of mice given 9-12 weeks of treatment secreted larger amounts of interferon-gamma (IFN gamma) and interleukin-2 (IL-2). Overall, these results suggest that the spontaneous regression phase is associated with changes in NK cell activity and lung cell lymphokine profile.

Mouse hypersensitivity pneumonitis: depletion of NK cells abrogates the spontaneous regression phase and leads to massive fibrosis

The contribution of natural killer cells (NK) in the progression of mouse hypersensitivity pneumonitis induced by repeated intranasal instillations with the thermophilic actinomycete Faeni rectivirgula was examined. These instillations determined a very large increase in the lung index (ca. twofold at 3 weeks), used as a measure of inflammation. In addition, this instillation was associated with a tenfold increase in the number of cells recovered in the bronchoalveolar lavage (BAL) at 3 weeks and thereafter. Most of these cells were macrophages, whereas T lymphocyte numbers increased at 6 weeks and thereafter. The instillations were also associated with a substantial fibrotic response in the lungs, as seen by large increases in hydroxyproline levels in the lungs. This fibrotic response, however, diminished after 6 weeks of instillations. Similarly, examination of histological preparations of lungs of challenged mice showed that F. rectivirgula induced inflammatory infiltrates of macrophages, lymphocytes, and neutrophils. The severity of the lesions were reduced in mice given more than 6 weeks of the actinomycete challenge. The involvement of NK cells on the development of this pulmonary pathology was determined by infusing F. rectivirgula-challenged mice with anti-NK 1.1 antibody. The depletion protocol was validated by verifying that such treatments effectively blocked lung NK cell activity. Such NK cell-depleted mice responded to the F. rectivirgula challenge with an increased lung index at 9 and 12 weeks, compared to mice challenged with F. rectivirgula and given control antibody. NK cell-depleted mice also responded to the actinomycete with a superior cellular recruitment in the BAL, with this increase mostly mediated by macrophages. Similarly, NK cell-depleted mice developed a fibrotic response that was much higher than that seen in control challenged mice, at 6, 9, and 12 weeks after initiation of the transnasal instillations. This was corroborated by scoring the severity of the histopathological lesions, which showed that NK cell-depleted mice had more severe lesions than challenged control mice. The importance of NK cells was confirmed by demonstrating that mice given anti-NK 1.1, challenged with F. rectivirgula and reconstituted with Percoll gradient-enriched lung NK cells had hydroxyproline levels at 9 and 12 weeks that were comparable to that seen in intact mice, as well as a histopathological score similar to control challenged mice. Overall, this suggests that in the course of a pulmonary inflammatory response, NK cells exert a suppressive effect on cellular recruitment in the BAL, contribute to down-regulating the inflammatory response, and are involved in blocking the appearance of fibrosis.

Murine hypersensitivity pneumonitis: bidirectional role of interferon-gamma

C57BL/6 mice were instilled intranasally with optimal doses [150 micrograms of antigen 3 days a week) of the actinomycete Faeni rectivirgula to induce an experimental hypersensitivity pneumonitis. Some control mice received normal rat IgG as controls, whereas other mice received 1 mg weekly of rat anti-murine interferon gamma (IFN-gamma) antibody by the intraperitoneal route and 200 micrograms by the intranasal route given 2 days before and during the challenge period before each instillation. Control mice developed a clear hypersensitivity pneumonitis characterized by an early neutrophilic response at 3 days and a later influx of mononuclear cells (nine- to tenfold increase in cell number. P less than 0.001 vs saline instilled mice at 4 weeks post-treatment). F. rectivirgula instillation determined a sharp increase in the lung index (80% increase in lung weight, P less than 0.005 vs saline treated mice), as well as a significant fibrosis at 4 weeks (twofold increase in lung hydroxyproline levels). Cytokine measurements showed that tumour necrosis factor alpha (TNF alpha) was present in the broncho-alveolar lavage (BAL) of challenged mice at 4 weeks when the BAL was obtained 8 hr after the last challenge (130 U/ml). Treatment of mice with the monoclonal antibody against IFN-gamma was associated with very few changes in the number of cells in the BAL of challenged mice. The lung index of challenged mice was significantly reduced by infusion of the anti-IFN-gamma antibody. Anti-IFN-gamma treatment resulted in decreased levels of TNF alpha in the BAL of F. rectivirgula after 4 weeks of treatment (56 U/ml, P less than 0.01). Moreover, depletion of endogenous IFN-gamma in F. rectivirgula-instilled mice resulted in a diminished lung fibrotic response (P less than 0.01 vs mice treated with F. rectivirgula and control antibody). We also studied the effect of exogenous IFN-gamma adminstration on the development of lung disease. Groups of mice received recombinant gamma interferon (IFN-gamma) (1000 U) intraperitoneally just before the first treatment and also daily, whereas controls received saline or IFN-gamma alone (no F. rectivirgula challenge). After 4 weeks of treatment, mice were killed and various markers of the disease were evaluated. As mentioned before, bronchoalveolar lavage (BAL) cell number was increased tenfold in mice treated with F. rectivirgula, whereas mice given F. rectivirgula and IFN-gamma had only a threefold increase in BAL cell number, determined mostly by a decrease in alveolar macrophage recruitment in the lungs.(ABSTRACT TRUNCATED AT 400 WORDS)

Transforming growth factor-beta is generated in the course of hypersensitivity pneumonitis: contribution to collagen synthesis

Mice of the C57BL/6 strain were instilled with optimal doses (150 micrograms/day for 3 days/wk) of the thermophilic actinomycete Faeni rectivirgula (also known as Saccharopolyspora rectivirgula or Micropolyspora faeni) to induce a hypersensitivity pneumonitis inflammation that mimics the human disease affecting certain occupational groups. This mouse model was characterized by a very significant alveolitis (3-fold increase in bronchoalveolar lavage [BAL] cell number at 48 h and a 10-fold increase at 3 wk). Also, total lung transforming growth factor (TGF-beta) was shown to be elevated in treated mice as early as 1 wk after the first instillation and increased gradually to 2.5 micrograms/lung at 3 wk (approximately 0.3 microgram/lung in saline-instilled controls). Intranasal instillation with F. rectivirgula was also associated with very significant increases in lung fibroblast collagen synthesis, starting at 2 wk. BAL macrophages from mice instilled with F. rectivirgula were found to release significantly more TGF-beta upon in vitro stimulation with zymosan beads than did BAL macrophages from saline-instilled mice. Finally, we show that supernatants from activated BAL macrophages of mice given F. rectivirgula increased quite significantly collagen synthesis in normal mouse lung fibroblasts. This increase could be abrogated by treating conditioned medium with a rabbit antibody against TGF-beta. Collectively, these data suggest that TGF-beta is generated in the course of experimental mouse hypersensitivity pneumonitis and contributes significantly to collagen synthesis.