Recent advances in pathogenesis of allergic alveolitis

Protein kinase D1 is essential for the proinflammatory response induced by hypersensitivity pneumonitis-causing thermophilic actinomycetes Saccharopolyspora rectivirgula

Hypersensitivity pneumonitis is an interstitial lung disease that results from repeated pulmonary exposure to various organic Ags, including Saccharopolyspora rectivirgula, the causative agent of farmer's lung disease. Although the contributions of proinflammatory mediators to the disease pathogenesis are relatively well documented, the mechanism(s) involved in the initiation of proinflammatory responses against the causative microorganisms and the contribution of signaling molecules involved in the host immune defense have not been fully elucidated. In the current study, we found that S. rectivirgula induces the activation of protein kinase D (PKD)1 in lung cells in vitro and in vivo. Activation of PKD1 by S. rectivirgula was dependent on MyD88. Inhibition of PKD by pharmacological PKD inhibitor Gö6976 and silencing of PKD1 expression by small interfering RNA revealed that PKD1 is indispensable for S. rectivirgula-mediated activation of MAPKs and NF-kappaB and the expression of various proinflammatory cytokines and chemokines. In addition, compared with controls, mice pretreated with Gö6976 showed significantly suppressed alveolitis and neutrophil influx in bronchial alveolar lavage fluid and interstitial lung tissue, as well as substantially decreased myeloperoxidase activity in the lung after pulmonary exposure to S. rectivirgula. These results demonstrate that PKD1 is essential for S. rectivirgula-mediated proinflammatory immune responses and neutrophil influx in the lung. Our findings also imply the possibility that PKD1 is one of the critical factors that play a regulatory role in the development of hypersensitivity pneumonitis caused by microbial Ags and that inhibition of PKD1 activation could be an effective way to control microbial Ag-induced hypersensitivity pneumonitis.

Identification of mycobacteria in peat moss processing plants: application of molecular biology approaches

Peat moss processing plant workers are exposed to high concentrations of bioaerosols. Although mycobacteria have been cultured from peat moss, no study has examined the workers' exposure to mycobacterial bioaerosols. We evaluated the presence of mycobacteria in air samples from peat moss processing plants using molecular biology approaches (cloning-sequencing and polymerase chain reaction (PCR)) and the workers exposure using immunoglobulin G (IgG) complexes to mycobacteria. In addition, species detected in air samples and in peat moss were compared. Two peat moss processing plants were chosen among 14 previously studied. A total of 49 clones were sequenced. Real-time PCR was also performed on the same air samples to evaluate the airborne concentration of mycobacteria and estimate exposure levels. Several Mycobacterium species were present in the air samples (M. malmoense, M. smegmatis, M. graceum, M. bohemicum, and M. interjectum). Mycobacterium avium was recovered by culture in peat moss but not in the air using the molecular approach. Total airborne Mycobacterium concentration was estimated at 8.2 x 10(8)/m3. Workers had IgG against the mycobacterial mix and M. avium, suggesting significant exposure. The findings from air samples, supported by IgG measurements, demonstrate that peat moss processing plant workers are exposed to mycobacteria in addition to other biological agents.

Respiratory syncytial virus replication is prolonged by a concomitant allergic response

Epidemiological studies show an association between early exposure to respiratory syncytial virus (RSV) and the development or exacerbation of asthma. This idea is supported by studies in mice that demonstrate worsened airway hyper-reactivity (AHR) when RSV-infected animals are exposed to allergen. The effect of allergen on RSV disease, however, has not been reported. Cotton rats (Sigmodon hispidus) that have been used as a model to study RSV pathogenesis were sensitized to extracts of Aspergillus fumigatus (Af), a common household mould. The allergic response to Af included eosinophilia, formation of granulomas and induction of Th2 type cytokines. RSV infection prior to allergen challenge resulted in exacerbation of the inflammatory response as well as increased airway responsiveness to methacholine. The exacerbated response was indeed dependent on virus replication. Virus replication in turn was influenced by the allergic response, with persistence in the noses for 2 days longer in animals challenged with allergen. This diminished clearance corresponded to decreased induction of mRNA for IFN-gamma, a Th1-type cytokine that is characteristic of viral infection. Treatment of RSV-infected Af-challenged animals with recombinant IFN-gamma reduced the allergic inflammatory response as well as the relative levels of Th1 and Th2 cytokine mRNA. However, this treatment did not reduce airway reactivity, showing that these pathologic and physiologic measures of exacerbated disease are independent. We speculate that the reciprocal effect of the allergic response on viral immunity may benefit the host by limiting exacerbation of physiologic responses that are IFN-gamma-dependent.

Hypersensitivity pneumonitis

PURPOSE OF REVIEW

Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis, is a granulomatous, inflammatory disease of the lungs caused by the inhalation of antigenic organic particles or fumes. The disease may present as an acute, subacute, or chronic illness. Episodes of acute and subacute HP usually resolve following cessation of antigen exposure. Chronic HP may be progressive, irreversible, and result in debilitating fibrotic lung disease. This review discusses current concepts regarding the diagnosis, pathogenesis, and treatment of HP.

RECENT FINDINGS

The pathogenesis of HP involves both type III and type IV hypersensitivity reactions that are mediated by immune complexes and Th1 T cells, respectively. Proinflammatory cytokines and chemokines activate alveolar macrophages, cause an influx of CD8+ lymphocytes into the lungs, facilitate granuloma formation, and promote the development of pulmonary fibrosis. IFN-gamma is essential for the development of HP and IL-10 appears to modulate the severity of disease. TNF-alpha and TGF-beta have been implicated in development of the pulmonary fibrosis that is seen in chronic HP. It has been shown that pigeon fanciers with HP have an increase in the frequency of HLA-DRB1*1305 and HLA-DQB1*0501 alleles, a decrease in the frequency of the HLA-BRB1*0802 allele, and an increased frequency of the TNF-2 (-308) polymorphism of the TNF-alpha promoter gene.

SUMMARY

A careful environmental and occupational history and establishment of exposure to a known inciting antigen are key factors in making the diagnosis of HP. Serum precipitating antibodies, bronchoalveolar lavage, and lung biopsy may be helpful in making the diagnosis. Avoidance of organic antigen exposure is the most important factor in the management of HP. Corticosteroids are indicated for the treatment of severe acute and subacute HP and for chronic HP that is severe or progressive. Long-term corticosteroid therapy for the treatment of chronic HP should be considered only if objective improvement in clinical signs, pulmonary function, or radiographic abnormalities is documented.

Use of co-immunoelectrodiffusion to detect presumed disease-associated precipitating antibodies, and time-course value of specific isotypes in bird-breeder's disease

BACKGROUND AND OBJECTIVE

The practical value of immunological diagnosis of bird-breeder's disease (BBD) is controversial, because of difficulties in distinguishing active disease patients from simple contact subjects. The aim of this study was to determine the diagnostic and prognostic value of (a) presumed disease-associated antibodies precipitating pigeon antigens (immunoglobulin A (IgAp) and P2 component), (b) characterization of specific isotypes (IgG, IgM, and IgA), and (c) antibody kinetics after antigen eradication.

METHODS

405 subjects (775 sera) in contact with birds were studied [by means of co-immunoelectrodiffusion (Co-IED) and enzyme-linked immunofiltration (ELIFA)] with soluble extracts of pigeon droppings and squab crop milk. These patients were divided into two groups based on the final clinical evaluation of the patients' physicians, which was taken as the gold standard (positive in 90 and negative in 315 cases).

RESULTS

On the basis of this gold standard, the detection of presumed disease-associated precipitating antibodies by Co-IED had a specificity of 95.5%, a sensitivity of 98.7%, an accuracy of 98%, and positive and negative predictive values of 95.5% and 98.7%, respectively. Most of the patients with a final positive diagnosis of BBD had specific IgG, IgM, and IgA antibodies by ELIFA. After antigen eradication, anti IgAp and/or P2 antibodies disappeared more rapidly than other precipitating systems.

CONCLUSION

Identification by Co-IED of precipitating immune complexes IgAp and/or P2 significantly reinforces the intrinsic credibility of immunological diagnosis of BBD. Compared to these presumed disease-associated precipitating antibodies, detection and time course of specific IgM, IgA antibodies, provided no additional diagnostic value or prognostic arguments to judge disease activity after antigen eradication.

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.

IV. Clinical aspects of delayed hypersensitivity in lungs: pathophysiology of hypersensitivity disorders in clinics

Hypersensitivity pneumonitis (HP) is an immunologically mediated lung disease of inhaled antigens. HP is not a uniform disease but rather a clinical complex syndrome characterized by varying intensities of responsiveness to different organic antigens. The main aetiological agents include thermophilic bacteria, fungi, animal proteins, and chemical compounds. A combination of host and environmental factors should be considered as a requisite to developing this disease. Although the antigens differ widely, the clinical syndromes that results are very similar. HP occurs mainly in non-smokers, and clinically it may be in acute, subacute, or chronic forms. The diagnosis of HP requires a constellation of clinic, radiographic, physiologic, pathologic, and immunologic criteria. HP is characterized by a diffuse and predominantly mononuclear cell inflammation, a partly granulomatous, immune disorder of alveolar regions that often involves the small airway. A strong evidence supports that delayed cell-mediated hypersensitivity mechanisms play a role in pathogenesis of HP. Studies performed on lung cells have demonstrated that cells bearing suppressor/cytotoxic phenotype characterize the lymphocytic alveolitis in patients with hypersensitivity pneumonitis. And also recently evidence has been provided indicating that a prominent role of T-helper 1 cell-mediated hypersensitivity with an imbalance in T-lymphocyte subsets, although the deposit of immune complex may participate in an acute form of the disease as well as in the early phase of the chronic form.

Germicidal ultraviolet irradiation in air conditioning systems: effect on office worker health and wellbeing: a pilot study

OBJECTIVES

The indoor environment of modern office buildings represents a new ecosystem that has been created totally by humans. Bacteria and fungi may contaminate this indoor environment, including the ventilation systems themselves, which in turn may result in adverse health effects. The objectives of this study were to test whether installation and operation of germicidal ultraviolet (GUV) lights in central ventilation systems would be feasible, without adverse effects, undetected by building occupants, and effective in eliminating microbial contamination.

METHODS

GUV lights were installed in the ventilation systems serving three floors of an office building, and were turned on and off during a total of four alternating 3 week blocks. Workers reported their environmental satisfaction, symptoms, as well as sickness absence, without knowledge of whether GUV lights were on or off. The indoor environment was measured in detail including airborne and surface bacteria and fungi.

RESULTS

Airborne bacteria and fungi were not significantly different whether GUV lights were on or off, but were virtually eliminated from the surfaces of the ventilation system after 3 weeks of operation of GUV light. Of the other environmental variables measured, only total airborne particulates were significantly different under the two experimental conditions--higher with GUV lights on than off. Of 113 eligible workers, 104 (87%) participated; their environmental satisfaction ratings were not different whether GUV lights were on or off. Headache, difficulty concentrating, and eye irritation occurred less often with GUV lights on whereas skin rash or irritation was more common. Overall, the average number of work related symptoms reported was 1.1 with GUV lights off compared with 0.9 with GUV lights on.

CONCLUSION

Installation and operation of GUV lights in central heating, ventilation and air conditioning systems of office buildings is feasible, cannot be detected by workers, and does not seem to result in any adverse effects.

Common respiratory viruses in lower airways of patients with acute hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP), a lung disease with "flulike" symptoms, results from repeated exposures to well defined, nonpathogenic antigens. This study examined whether respiratory viruses are present in the lower airways, the likely site of hypersensitivity reaction, in patients with HP. The polymerase chain reaction (PCR) method was used to test for 10 common respiratory viruses in bronchoalveolar lavage (BAL) cells obtained from patients with acute HP and from unexposed healthy volunteers. Immunocytochemistry was subsequently used to localize viral proteins within BAL cells. The results of PCR showed that influenza A virus was the most frequently detected virus in the BAL cells of our study patients (six of 13) and control subjects (two of six). Influenza A proteins were detected within alveolar macrophages in nine of 13 patients and in two of six control subjects. The number of total BAL cells, but not lymphocytes, was higher in patients with documented influenza A proteins than in patients with no influenza A proteins (p = 0.017) and correlated with the proportion of influenza-A-positive alveolar macrophages (r = 0.7; p = 0.036). This report documents the presence of viruses in the lower airways of patients with acute HP. The findings may imply a potential role for influenza A in the modulation of HP during antigen exposure.

Interleukin-10 modulates the severity of hypersensitivity pneumonitis in mice

Hypersensitivity pneumonitis (HP) is an inflammatory lung disease characterized by granuloma formation. We recently showed that interferon-gamma (IFN-gamma) is essential for inflammation and granuloma formation in HP. Interleukin-10 (IL-10) counteracts many of the biologic effects of IFN-gamma, suggesting that IL-10 modulates inflammation and granuloma formation in HP. We compared the expression of HP in C57BL/6 mice that lack IL-10 (IL-10 knockout [KO]) with that in wild-type (WT) littermates. IL-10 KO and WT mice were exposed to the thermophilic bacteria Saccharopolyspora rectivirgula or to saline alone for 3 wk. The IL-10 KO mice had higher cell counts in their bronchoalveolar lavage fluid (2.85 +/- 0. 43 x 10(6)) than did WT mice (1.4 +/- 0.3 x 10(6)/ml; P < 0.03), with a more prominent neutrophil response. They also had greater inflammation after antigen exposure than did the WT mice (P < 0. 0001). There was increased upregulation of IFN-gamma, IL-1, and tumor necrosis factor-alpha (TNF-alpha) mRNAs in the lungs of IL-10 KO mice. Adenovirus-mediated gene transfer of IL-10 to the liver of IL-10 KO mice reduced the inflammation from that seen in WT mice. These studies show that IL-10 has important anti-inflammatory properties in HP, and that lack of this cytokine leads to a more severe granulomatous inflammatory response.

Biomarkers of exposure, antibodies, and respiratory symptoms in workers heating polyurethane glue

OBJECTIVES

The pathogenic basis of respiratory disorders associated with isocyanates are still obscure. One reason for this is the lack of good estimates of human exposure. In this study exposure was estimated by measurement of isocyanate metabolites in biological samples.

METHODS

In a factory using isocyanate based polyurethane (PUR) glue, isocyanate concentrations in air were measured by liquid chromatography. Samples from 174 employees were analysed for metabolites of 4,4'-methylene diphenyl diisocyanate (MDI) in plasma (P-MDX) and urine (U-MDX). After hydrolysis, 4,4'-methylenedianiline was measured by gas chromatography-mass spectrometry (GC-MS). The employees were screened for work related respiratory symptoms and tested for specific immunoglobulin E (IgE) and IgG antibodies directed against isocyanate conjugated to human serum albumin.

RESULTS

The time weighted isocyanate concentrations in air were low (MDI < 0.2-7; hexamethylene diisocyanate (HDI) < 0.1-0.7; 2,6-toluene diisocyanate (TDI) < 0.1 microgram/m3). All subjects had detectable P-MDX and U-MDX. There were significant associations between the estimates of exposure to thermal degradation products of an MDI based glue and P-MDX (range < or = 0.10-5.5 micrograms/l); and U-MDX (< or = 0.04-5.0 micrograms/g creatinine); in cases of heavy exposure. P-MDX and U-MDX were associated with each other (r = 0.64; P = 0.0001), work related symptoms (P-MDX: P = 0.03; Mann-Whitney U test), and serum concentrations of MDI specific IgG antibodies (r = 0.26; P = 0.0007). Unexpectedly, high P-MDX and U-MDX concentrations were also encountered in workers cutting textile (P-MDX 2.4-4.5 micrograms/l; U-MDX 0.81-3.8 micrograms/g creatinine); the reason is still unknown. Equally unexpected, there were significant negative associations between P-MDX and liver function tests.

CONCLUSIONS

The results clearly show the value of biomarkers for isocyanate exposure; in particular, P-MDX is useful. Further, these results show the risk connected with thermal degradation of PUR.

Cellular immune response to fractionated avian antigens by peripheral blood mononuclear cells from patients with pigeon breeder's disease

Pigeon breeder's disease (PBD), a form of hypersensitivity pneumonitis caused by repeated inhalation of antigens of pigeon origin, is characterized by a diffuse inflammation of the lower respiratory tract. Although a variety of immunologic and nonimmunologic mechanisms have been described in the development of the disease, the pathogenesis is still far from clear. In this study we analyzed the T-lymphocyte proliferative response to a variety of avian antigens with use of peripheral blood mononuclear cells from 11 patients who had PBD and 10 healthy volunteers. We used a new method based on avian antigen-bearing nitrocellulose particles derived from Western blots to study the T-cell proliferative response to 15 antigenic fractions obtained from pigeon serum. With this technique, complex mixtures of antigens can be fractionated by polyacrylamide gel electrophoresis, transferred to nitrocellulose membranes, and used for T-cell proliferation assays with selected antigenic determinants. A wide variety of responses were observed, and there were no reproducible patterns of reaction within either group. Nine of 10 healthy subjects responded to some soluble fractions. However, patients with PBD displayed the strongest response and responded to a significantly greater number of antigenic fractions. Fraction 2, representing a 220 kd molecular weight protein, was the only immunodominant antigen when both groups were compared; it was recognized by 73% of the patients with PBD and by only 20% of control subjects (p < 0.03). These findings show that T lymphocytes of patients with PBD recognize a wide range of bird proteins, which induce marked T-cell proliferation.

Soluble intercellular adhesion molecule-1 (ICAM-1) in sera and bronchoalveolar lavage (BAL) fluids of extrinsic allergic alveolitis

ICAM-1 plays an important role in inflammatory diseases. We analysed ICAM-1 expression on BAL fluid cells and measured soluble ICAM-1 (sICAM-1) concentrations in sera and BAL fluids from patients with extrinsic allergic alveolitis (EAA). We found significantly increased cellular ICAM-1 expression on BAL fluid lymphocytes and alveolar macrophages, and significantly increased values of circulating and BAL fluid sICAM-1 in EAA patients compared with controls. Successive measurement showed prompt decrease of both sICAM-1 values in EAA patients during periods when antigen exposure was prevented. In BAL fluids from EAA patients, sICAM-1 values significantly correlated to neutrophil and ICAM-1+ lymphocyte counts. In EAA patients, circulating and BAL fluid sICAM-1 values has significant negative correlations to values of carbon monoxide diffusing capacity and to time intervals between last episode and sample collection. However, these values had significant positive correlation to values of alveolar-arterial oxygen pressure difference. In EAA, antigen exposure appears to induce cellular ICAM-1 expression on BAL fluid cells, and also appears to up-regulate shedding of ICAM-1 in the alveolar lining fluid and in the circulation. The sICAM values appear to reflect disease activity of EAA.

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.

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.

Serum IgG antibodies to mold spores in two Norwegian sawmill populations: relationship to respiratory and other work-related symptoms

Wood trimmers and planing operators from two separate sawmill populations (N = 303 and 170) were studied by serology assessment and a self-administered questionnaire. IgG antibodies to Rhizopus microsporus ssp. rhizopodiformis, Paecilomyces variotii, and Aspergillus fumigatus were measured by ELISA. The questionnaire included questions about general respiratory symptoms and symptoms after handling moldy timber. Personal exposure of wood trimmers to mold spores and wood dust was measured in one part of the sawmills. R. microsporus was the most prevalent mold assessed by serology. Antibody levels were higher and symptoms suggestive of mucous membrane irritation, chronic nonspecific lung disease, allergic alveolitis, and organic dust toxic syndrome were more frequently reported by wood trimmers than by planing operators. The mean level of IgG antibodies to R. microsporus in sawmill workers working in the same work area was the best predictor of symptoms in both populations. The consistent results indicate that exposure to spores of R. microsporus may cause several respiratory symptoms in wood trimmers.

Activation of blood neutrophils in acute episodes of farmer's lung

Farmer's lung often presents clinically as recurring acute episodes several hours after exposure to moldy hay. During these episodes the blood neutrophil count increases. Because activated neutrophils release toxic oxygen metabolites and proteinases, we hypothesized that the pulmonary reaction in farmer's lung may be induced by the secretory products of activated neutrophils. To evaluate this concept, we quantified the respiratory burst of separated blood neutrophils from patients with farmer's lung (n = 12) during standardized exposure tests with moldy hay. The respiratory burst of these cells was evaluated by measuring zymosan-stimulated and lucigenin-amplified chemiluminescence (CL). Asymptomatic farmers (n = 12) and normal volunteers with no prior exposure to moldy hay (n = 15) were used as control subjects. As expected, following exposure in the group of patients with farmer's lung, striking changes in VC, TLCO, and PaO2 were observed, whereas there were only minor changes in these parameters in both control groups. In all three groups a considerable increase in the blood leukocyte count was observed. The CL response of the blood neutrophils from patients with farmer's lung 6 h after exposure was significantly higher than before or 1 h after exposure (p < 0.05 for both comparisons), whereas there was no significant change in the CL response in either control group during the observation period. Our results indicate that antigen inhalation induces an increase in the number of circulating neutrophils in patients and controls, but in patients with an acute episode of farmer's lung the neutrophils are primed for an enhanced respiratory burst and may thereby damage the lung.

Relationships between characteristics of exposure to pigeon antigens. Clinical manifestations and humoral immune response

An extensive clinical study has been performed on pigeon breeders in the Canary Islands. Three hundred forty-three subjects have participated in this study through the filling of a clinical and epidemiologic questionnaire. A venous blood sample was also taken from each fancier for a further serologic analysis. Detection of specific IgG antibodies was made by an indirect enzyme-linked immunosorbent assay (ELISA) using pigeon serum as antigenic material. Twenty-nine (8 percent) breeders fulfilled the "classic" pigeon breeders' disease (PBD) criteria. One hundred six (31 percent) had rhinitis, 62 (19 percent) had immediate bronchial symptoms, and 51 (15 percent) suffered from chronic bronchitis. A significant level of specific IgG was detected in 139 (40 percent) cases. Rates were correlated with pneumonitis symptomatology (p < 0.001) and with chronic bronchitis (p < 0.05). There was a significant association between the number of pigeons and the level of sensitization (p < 0.001). Finally, a statistical relationship between the intensity of exposure and specific IgG response was also found (p < 0.001). Titers of specific IgE could not be related either to the reported symptomatology in the questionnaire or to any of the exposure parameters analyzed.

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.

[Salami and extrinsic allergic alveolitis: a new occupational disease in Switzerland]

The authors report a case of extrinsic allergic alveolitis in a patient working in an industrial butchery where she is involved in the preparation of dry sausages. The molds proliferating at the surface of these sausages, molds from the Penicillium family, are responsible for the disease. The respective value of laboratory tests such as the presence of precipitating antibodies and the analysis of the cellularity of the bronchoalveolar lavage are discussed. Whenever a patient presents with clinical symptoms suggestive of extrinsic allergic alveolitis a detailed search for any type of exposure linked to the professional milieu is required, so as to propose adequate modifications in work conditions or work place.

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)

Murine hypersensitivity pneumonitis: interleukin-4 administration partially abrogates the disease process

C57BL-6 inbred mice were given intranasal instillations of Faeni rectivirgula (150 micrograms/day, 3 days a week for 3 weeks) to produce a lung inflammatory reaction which mimics Farmers' lung in humans. Challenged mice developed a strong inflammatory response in their lungs, based on various markers (lung index, bronchoalveolar cell number, fibrosis). The effect of interleukin-4 (IL-4) was studied by infusing mice intraperitoneally with 100, 1000 or 10,000 units of IL-4 weekly during the challenge period. It was shown that IL-4 infusion decreased the inflammatory response, as seen by a decreased lung index (1.7 in mice given F. rectivirgula and 10(3) U IL-4 and 1.31 in mice given antigen and 10(4) U IL-4 weekly versus 2.3 in mice instilled with F. rectivirgula). Interleukin-4 infusion also partially abrogated the F. rectivirgula-induced alveolitis, as seen by a decrease in cell numbers in the broncho-alveolar lavage (BAL) (1.3 x 10(5) cells in saline-instilled mice; 8.3 x 10(5) cells in mice given 10(3) U IL-4 and F. rectivirgula; 3.2 x 10(5) cells in mice given antigen and 10(4) U IL-4; 1.8 x 10(6) cells in mice given F. rectivirgula only). Also, it was apparent that IL-4 administration could partially block the appearance of the fibrosis induced by F. rectivirgula (220 micrograms of hydroxyproline/lung in challenged mice; 170 micrograms/lung in challenged mice given 10(3) U IL-4; 131 micrograms/lung in mice given antigen and 10(4) U IL-4 and c. 100 micrograms/lung in control animals). Infusion of 10(2) U IL-4 weekly had no statistical effect on any marker of inflammation.(ABSTRACT TRUNCATED AT 250 WORDS)

T cells in hypersensitivity pneumonitis: effects of in vivo depletion of T cells in a mouse model

C57BL/6 mice were given intranasal instillation of optimal doses of the actinomycete Faeni rectivirgula 150 micrograms/mouse 3 days/wk), an important offending agent causing hypersensitivity pneumonitis. This instillation was associated with a very significant increase in the lung weight of the mice and also a large increase (10-fold) in the number of cells recovered from the bronchoalveolar lavage (BAL) of instilled mice. Also, this instillation was associated with a very significant fibrosis at 4 and 8 wk (2-fold increase in hydroxyproline levels in the lungs). We determined the effect of depleting certain T-cell subsets on the progression of this inflammatory disease. Elimination of the L3T4 subset did not significantly affect the increase in the lung index, the lung cellular influx, or its profile. Fibrosis was also unaffected by this depletion of L3T4+ cells. Similarly, depletion of Lyt2+ (CD8+) cells did not lead to significant changes in these disease parameters. Depletion of all T cells (Thyl+) was also ineffective at modifying the number of infiltrating cells and the lung index score. However, identification of cell types in BAL showed that mice depleted of Thyl+ cells had a cellular influx that was almost exclusively neutrophilic throughout the instillation period, whereas control mice developed only a transient neutrophilic response to F. rectivirgula instillation, which was replaced by a recruitment of mononuclear cells, mostly macrophages. Also, depletion of Thyl+ cells before and during F. rectivirgula challenge had no effect on tumor necrosis factor-alpha levels in the BAL of treated mice (63 +/- 13 U/ml in anti-Thy1. 2 antibodies treated versus 52 +/- 10 U/ml in the BAL of control mice given F. rectivirgula).(ABSTRACT TRUNCATED AT 250 WORDS)

Murine hypersensitivity pneumonitis: a study of cellular infiltrates and cytokine production and its modulation by cyclosporin A

The progression of hypersensitivity pneumonitis (HP) was evaluated in mice repeatedly challenged with the actinomycete Faeni rectivirgula (Micropolyspora faeni) (90 or 180 micrograms), at the cellular level and at the mediator level. Instillation of F. rectivirgula by the intranasal route determined a granulomatous inflammation in the lungs of animals correlated with a dramatic increase (5- to 6-fold) in cellularity in the bronchoalveolar space and an increase in the percentage of lymphocytes. Disease in mice was also correlated with high spontaneous release of the cytokines interleukin-1 (IL-1) (60 U/ml), interleukin-6 (IL-6) (72 U/ml), and tumor necrosis factor-alpha (TNF-alpha) (56 U/ml) in the bronchoalveolar lavage (BAL) fluid, as well as by an enhanced capacity for cytokine release by macrophages upon stimulation with F. rectivirgula. It was also found that the pulmonary inflammation was correlated with a 60 to 70% increase in total lung weight after 4 wk and a significant lung fibrosis as seen by a 2-fold increase in lung hydroxyproline levels. Treatment of challenged mice with cyclosporin A (CyA) led to an abrogation of the disease as seen by an abrogation of the increase in lung index, lack of IL-1 and TNF-alpha release in the BAL. CyA did not, however, completely prevent the alveolitis as seen by the cellular infiltrate (2- to 3-fold in BAL cell increase). It also did not prevent the T-lymphocyte recruitment associated with HP, although these cells did not proliferate in response to the F. rectivirgula antigen, in contrast to BAL cells from F. rectivirgula-challenged mice treated with excipient only.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumor necrosis factor plays an essential role in determining hypersensitivity pneumonitis in a mouse model

We examined the importance of the cytokine tumor necrosis factor-alpha (TNF-alpha) in a mouse model of hypersensitivity pneumonitis (HP). Mice of the C57BL/6 strain were instilled intranasally 3 days/wk for 3 wk with 150 micrograms of the actinomycete Faenia rectivirgula (Micropolyspora faeni) to induce HP as a model of farmer's lung. This experimental model was associated with a progressive inflammation in the lungs of challenged mice, seen histologically as cellular infiltrates of large quantities of macrophages and lymphocytes and some neutrophils. The disease in challenged mice treated with a control rabbit serum was also associated with a substantial release of tumor TNF-alpha (up to 80 U/ml of TNF-alpha in the bronchoalveolar lavage [BAL] at 3 wk after beginning of treatment) and interleukin-1, which peaked at 1 wk (approximately 300 U/ml) and diminished thereafter. A very large increase in BAL cell number (11-fold increase versus saline controls) and an enhanced release potential for TNF-alpha by alveolar macrophages was also seen. Lung fibrosis was also evident in challenged animals, as demonstrated by a 2-fold increase in hydroxyproline levels. Infusion of challenged mice with a rabbit polyclonal antibody against TNF-alpha (2 mg/wk) completely abrogated the disease, as mice so treated had normal lung histology. Anti-TNF-alpha blocked cellular recruitment in the lungs (only a 2-fold increase at week 3); it also completely abolished TNF-alpha secretion in the BAL and drastically reduced interleukin-1 levels in this fluid. Anti-TNF-alpha also abolished lung index increases and lung fibrosis, with both parameters similar to that of saline-instilled mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Mast cells in bronchoalveolar lavage fluid and in transbronchial biopsy specimens of patients with farmer's lung disease

Recently, an increased number of mast cells have been reported in bronchoalveolar lavage fluid (BAL) of patients with farmer's lung disease. Some authors pointed out the pathogenetic importance of mast cells in farmer's lung on the basis of their correlation with the activity of the disease, with the BAL lymphocyte counts, and with the markers of lung fibrosis. To determine whether BAL reflects the histologic aspects of the lung histologic features in patients with farmer's lung disease, mast cells recovered from lavage fluid were compared with tissue sections from transbronchial lung biopsies in 15 patients. Mast cell counts in BAL and lung biopsy specimens were significantly correlated (r = 0.88; p less than 0.01), while no other correlations between BAL inflammatory cells and tissue mast cells were found. In lung tissue, there were four times the increased number of mast cells in respect to the control group (84.4 +/- 28.8 vs 20.4 +/- 13.4 mast cells per square millimeter); 83.2 percent of mast cells were found in the alveolar septa, 14.9 percent within alveoli, 0.7 percent among alveolar lining cells, and 1 percent along blood vessels. No mast cells were located within alveoli in controls. In BAL, only lymphocyte and mast cell counts (56.4 +/- 18.6 percent, p less than 0.001; 3.9 +/- 1.5 5 percent, p less than 0.001, respectively) were significantly increased. Our data suggest that in farmer's lung disease, BAL correctly samples the alveolitis. Mast cells, such as lymphocytes, seem to be primary inflammatory cells involved at the site of the disease activity.

Hypersensitivity pneumonitis: whole Micropolyspora faeni or antigens thereof stimulate the release of proinflammatory cytokines from macrophages

Hypersensitivity pneumonitis (HP) is an allergic granulomatous interstitial lung disease resulting from a reaction of selected individuals to repeated inhalations of certain antigens. HP is characterized by chronic inflammation, and the development of the disease seems to be immunologically mediated. In farmer's lung, the source of provoking antigen has been found to be actinomycetes such as Micropolyspora faeni. In this study, we show that M. faeni, or antigens thereof, stimulate strong release of proinflammatory cytokines from blood monocytes and alveolar macrophages obtained from nonfarmer volunteers and naive mouse peritoneal macrophages. Interleukin-1 (IL-1) was produced by human alveolar macrophages and murine peritoneal macrophages in response to whole M. faeni and antigens thereof. IL-1 activity was detected in the supernatants at 12 h of incubation and was maximal by 24 to 36 h (200 to 400 U/ml of IL-1). A rabbit antiserum to IL-1 alpha and IL-1 beta neutralized the thymocyte-stimulating activity of the supernatants. Moreover, M. faeni (1 to 100 micrograms of antigen) elicited a strong secretion of tumor necrosis factor-alpha (TNF-alpha) from human alveolar macrophages and monocytes as well as mouse peritoneal macrophages, where 1 micrograms of M. faeni elicited the secretion of approximately 100 U of TNF-alpha from 2 x 10(5) macrophages, and 100 micrograms stimulated the release of approximately 1,000 U of bioactive TNF-alpha. One particle of whole M. faeni per cell was sufficient to induce copious release of TNF-alpha from macrophages or monocytes (100 U of bioactive TNF-alpha; 1,000 pg/ml of antigenic TNF-alpha as seen by radioimmunoassay). Both IL-1 and TNF-alpha productions stimulated by M. faeni were not abrogated by inclusion of polymyxin B. We propose that the direct stimulation of cytokines by M. faeni or antigens thereof may play an important role in HP.

Hypersensitivity pneumonitis

Hypersensitivity pneumonitis or extrinsic allergic alveolitis is an immunologically mediated lung disease caused by repeated inhalations of organic antigens. The basic histologic lesion consists of a diffuse mononuclear cell infiltration of alveolar wall, alveoli, terminal bronchioles, and neighboring interstitium. The inflammation is often followed by granulomas, which then may progress to fibrosis. Although there is no single radiologic, physiologic, or immunologic test specific for hypersensitivity pneumonitis, the diagnosis can often be suspected on the basis of a compatible temporal relationship of pulmonary symptoms to the history of environmental or occupational exposure. Once the diagnosis is suspected, the presence of serum precipitating antibodies (IgG), suppressor cytotoxic lymphocytosis in bronchoalveolar lavage fluid, and granulomatous alveolitis in lung biopsy specimens are extremely helpful in confirming the diagnosis. In patients where the diagnosis is confirmed, avoidance of the causative antigen is the best therapy, although corticosteroids are used to suppress inflammation. Once the fibrosis is set in, the patient may gradually slide into respiratory failure, cor pulmonale, and death.