Longitudinal study of alveolitis in hypersensitivity pneumonitis patients: an immunologic evaluation

Interleukin 12, interleukin 18, and tumor necrosis factor alpha release by alveolar macrophages: acute and chronic hypersensitivity pneumonitis

BACKGROUND

Hypersensitivity pneumonitis (HP) is characterized by a granulomatous inflammation and may show various forms of clinical presentation, such as the acute, subacute, and chronic forms. The TH1-associated cytokines interleukin (IL) 12 and IL-18 and tumor necrosis factor alpha (TNF-alpha) may be involved in the pathogenesis of both the acute and chronic forms of HP.

OBJECTIVE

To compare the release of IL-12, IL-18, and TNF-alpha from bronchoalveolar lavage (BAL) macrophages in these 2 forms of HP.

METHODS

Patients underwent BAL 0 to 6 days after the last antigen exposure. Alveolar macrophages (AMs) from BAL in 6 patients with acute HP, 16 with chronic HP, and 11 controls were cultured for 24 hours. Cytokines in the culture supernatants were measured by enzyme-linked immunosorbent assay.

RESULTS

The production of IL-12, IL-18, and TNF-alpha by AMs was increased in patients with both acute and chronic forms in either the absence or presence of lipopolysaccharide compared with controls. The levels of IL-12, IL-18, and TNF-alpha showed no difference between patients with acute and chronic HP. The spontaneous production of IL-12, IL-18, and TNF-alpha did not correlate with the CD4/CD8 ratio in BAL. The spontaneous and lipopolysaccharide-stimulated release of IL-12 showed a positive correlation with the percentage of lymphocytes (r = .470, P = .03; r = .496, P = .02; respectively) in BAL.

CONCLUSIONS

This study demonstrates that an increased release of IL-12, IL-18, and TNF-alpha by AMs is associated with both the acute and chronic forms of HP.

Hypersensitivity pneumonitis: an immunopathology review

CONTEXT

Hypersensitivity pneumonitis (HSP) is an immunologically mediated alveolar and interstitial lung disease caused by repeated inhalation of organic dusts and some occupational agents.

OBJECTIVE

The pathogenesis of HSP is uncertain. A number of unexplained features of HSP remain, namely (1) why do so few exposed individuals develop clinical HSP, (2) what triggers an acute episode after prolonged periods of previous sensitization, and (3) what leads to disease progression. This article considers these issues and aims to discuss and clarify current concepts in pathogenesis.

DATA SOURCES

Pertinent literature review in conjunction with the author's personal interpretive opinion.

CONCLUSIONS

Current data suggest that individuals with a T(H)1 dominant response are likely to develop clinical disease. There is also some evidence that genetic factors such as polymorphisms in the major histocompatibility complex, tumor necrosis factor alpha, and tissue inhibitor of metalloproteinase 3 are associated with the development of or resistance to the disease.

Expansion of Pulmonary CD8+CD56+ Natural Killer T-Cells in Hypersensitivity Pneumonitis

BACKGROUND

Natural killer T (NKT) cells, a newly identified subgroup of T cells with immunoregulatory function, may be implicated in the pathogenesis of interstitial lung disease (ILD).

METHODS

We used multiparameter flow cytometry with antibodies to CD3, CD4, CD8, CD14, CD19, CD45, CD16/56, CD56, CD161, and Valpha24 invariant T-cell receptor (TCR) in BAL fluid (BALF) to examine the frequency and distribution of pulmonary NKT cells in several cases of ILD. We included 57 patients with sarcoidosis and 17 patients with hypersensitivity pneumonitis.

RESULTS

We found significantly higher frequencies of pulmonary NKT cells in patients with hypersensitivity pneumonitis in comparison to the other study patients with ILD (median proportion of NKT cells, 11%; range, 3 to 38%; vs 3%; range, 0 to 16%; p < 0.0001). In contrast, there was no difference in the proportion of conventional natural killer cells. We found that a major subset of NKT cells in the BALF of patients with hypersensitivity pneumonitis was a CD8+CD56+ population that did not express the invariant TCR.

CONCLUSIONS

These results suggest the involvement of NKT cells in the pathogenesis of hypersensitivity pneumonitis.

Extrinsic allergic alveolitis

Extrinsic allergic alveolitis (also known as hypersensitivity pneumonitis) is caused by repeated inhalation of mainly organic antigens by sensitized subjects. This induces a hypersensitivity response in the distal bronchioles and alveoli and subjects may present clinically with a variety of symptoms. The aims of this review are to describe the current concepts of the immunological response, the diverse clinical presentation of this disease, the relevant investigations and management, and areas for future studies.

New aspects of hypersensitivity pneumonitis

PURPOSE OF REVIEW

Hypersensitivity pneumonitis (HP) represents a complex pulmonary disorder of varying intensity and clinical presentation, which is characterized by a diffuse Tc1 immune response of lung parenchyma and airways in patients previously sensitized to one of more than 300 etiologic agents that may favor the HP reaction. This review describes recent data that have clarified some of the events that govern the development of the hypersensitivity reaction following exposure to the causative agents involved in this disease.

RECENT FINDINGS

A number of recent data clearly demonstrate that several cytokines and chemokines, which are secreted at sites of disease activity, participate in the pulmonary inflammatory responses taking place in the lung of patients with HP.

SUMMARY

The past few years have seen outstanding advances in the understanding of immunologic and molecular events involved in the pathogenesis of HP. It is possible that these data could allow the discovery of therapeutic targets in individuals chronically exposed to HP antigens and evolving towards pulmonary fibrosis.

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.

T cells in the lung of patients with hypersensitivity pneumonitis accumulate in a clonal manner

Hypersensitivity pneumonitis (HP) is characterized by an alveolitis sustained by CD8(+) T lymphocytes showing a limited expression of the T cell receptor (TCR). We previously demonstrated that a bias in T cell selection occurs in the lower respiratory tract of patients with HP, with a compartmentalization in the lung of CD8(+) T cells bearing (TCR)-beta variable (TCRBV) #2, 3, 5, 6, 8, and 13 gene segments. We herein characterized the clonal T cell populations present in the lung and in the blood of patients with HP. Heteroduplex analyses, cloning, and sequencing T cells bearing TCR indicate oligoclonal expansions of T cells expressing homologous or identical complementary-determining region 3. Furthermore, T cell clones isolated from the two compartments expressed similar, sometimes identical, junctional regions. Removal from antigenic exposure led to the disappearance of T cell clones. Our findings indicate that expansions of T lymphocytes bearing clonal TCRBV region gene segments take place in the lung of patients with HP during exposure. The evidence that identical T cell clones are present in the lung and the blood of the same patient suggests that the immune reaction occurring at lung level gives rise to a systemic reaction.

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.

Takes your breath away--the immunology of allergic alveolitis

Extrinsic allergic alveolitis (synonym: hypersensitivity pneumonitis) is caused by inhaling antigenic aerosols which induce hypersensitivity responses in susceptible individuals. It is an interstitial inflammatory disease affecting the distal, gas-exchanging parts of the lung, in contrast to allergic asthma where the inflammation is more proximal, affecting the conducting airways. The aims of this review are to describe current concepts of the immunology of this model of lung inflammation, to describe some of the constitutional and environmental characteristics which affect disease susceptibility and development, and to describe topics for prospective study.

[Extrinsic allergic alveolitis]

Extrinsic allergic alveolitis (EEA) is a lung disease mediated by immunologic mechanisms and induced by repeated exposure to organic dusts. EAA in children are mostly observed around 10 years of age. Subacute clinical presentation is the most frequent. Diagnosis is based on simultaneous presence of most of the following arguments: exposure to a known risk factor, spontaneous improvement after cessation of the exposure, identification of specific precipitins, demonstrative aspects on X-ray and tomodensitometry, and CD8+ lymphocytosis in bronchoalveolar lavage. Lung biopsy and specific provocation test are rarely necessary for diagnosis. Treatment is based on total eviction from inhaled antigen and on oral corticosteroids in acute and subacute forms.

Flock worker's lung: broadening the spectrum of clinicopathology, narrowing the spectrum of suspected etiologies

STUDY OBJECTIVES

Workers in the nylon flocking industry recently have been found to be at increased risk of chronic nongranulomatous interstitial lung disease. Although a spectrum of cytologic and histopathologic abnormalities has been observed, nonspecific interstitial pneumonia, lymphoid nodules, and lymphocytic bronchiolitis predominated in the 19 previously reported cases of flock worker's lung. Here we describe five additional patients who appear to expand the histopathologic spectrum and add to the evidence suggesting a causative role for respirable-sized nylon fragments.

METHODS

We studied all North American patients (n = 5) found in 1998 to satisfy our previous case definition of flock worker's lung. Two pulmonary pathologists independently reviewed each biopsy specimen.

RESULTS

All five patients reported cough and dyspnea. Only one patient had crackles on chest auscultation. High-resolution CT scan, interpreted with attention to subtle ground-glass attenuation, remained a highly sensitive diagnostic test. Pulmonary function tests and plain chest radiograph were less sensitive. One patient's wedge biopsy showed previously described prototypical findings. Two others had transbronchial biopsies showing some of the same features. The fourth patient's wedge biopsy showed desquamative interstitial pneumonia. The fifth patient had bilateral synchronous adenocarcinoma but with radiographic evidence of diffuse interstitial fibrosis. These 5 patients and the 19 patients studied previously were exposed to nylon flock manufactured by a rarely used cutting technology.

CONCLUSION

Findings in these five patients appear to broaden the spectrum of the clinicopathology of flock worker's lung and add to the evidence incriminating respirable-sized nylon particulates produced during the manufacture and use of rotary-cut nylon flock.

Skewing of the CD8+ T-cell repertoire in the lungs of patients with systemic sclerosis

Pulmonary parenchymal involvement in SSc is characterized by alveolitis and interstitial fibrosis, with an increased number of CD8+ T cells in BAL fluids. This study analyzed the diversity of the alphabeta T-cell repertoire in peripheral blood and BAL fluids from seven SSc patients, looking for evidence of antigen-driven selection of T cells in the lungs. A reverse transcriptase-polymerase chain reaction technique was used to amplify rearranged TCR transcripts from unfractionated, CD4+, and CD8+ T cells. Nearly all AV and BV gene families were expressed in SSc patients and most had similar levels of expression in blood and BAL samples. Next, the diversity of TCR junctional region lengths was assessed, using sequencing gel electrophoresis. Many V gene families had a Gaussian distribution of their junctional region lengths. However, some V gene families had an abnormal pattern of junctional lengths, with skewing away from a Gaussian distribution, including predominance of one or two lengths. This suggests selected expansion of T cells expressing those V genes. Alterations in TCR junctional region lengths were most prominent in bronchoalveolar CD8+ T cells, with similar patterns of skewing in several patients and in one patient over time. Sequence analysis of AV14 and BV17 junctional regions confirmed the oligoclonal character of expansion of bronchoalveolar CD8+ T cells.

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.

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.

The identification of hypersensitivity pneumonitis

The clinical history may point suspicion at a specific sensitizer. Brief, intermittent exposure produces acute, often reversible disease, frequently misdiagnosed as viral or bacterial pneumonia. Long-term exposure fuels the insidious development of chronic, disabling disease with minimal reversibility.

Relationship between plasma cell levels and profile of bronchoalveolar lavage fluid in patients with subacute extrinsic allergic alveolitis

BACKGROUND

Plasma cells are usually absent in bronchoalveolar lavage (BAL) fluid. Extrinsic allergic alveolitis is associated with increased numbers of T and B lymphocytes in BAL fluid, as well as the presence of a few plasma cells. The aim of this study was to investigate whether there is a relationship between the presence of plasma cells and other cells, and immunoglobulin levels in BAL fluid of patients with extrinsic allergic alveolitis.

METHODS

Thirty non-smoking patients with extrinsic allergic alveolitis who had a bronchoalveolar lavage 2-7 days after their last exposure to the causative antigen were selected, retrospectively.

RESULTS

Patients suffering from extrinsic allergic alveolitis with plasma cells in the BAL fluid (n = 18) had increased absolute numbers of lymphocytes, eosinophils and mast cells, a decreased percentage of alveolar macrophages and lower CD4/CD8 ratio, as well as higher immunoglobulin levels, when compared with patients with extrinsic allergic alveolitis having no plasma cells in the BAL fluid (n = 12).

CONCLUSIONS

The results suggest a relationship between the presence of plasma cells and the other constituents in BAL fluid and a more intense alveolitis. In addition there was a positive relationship between the number of plasma cells in BAL fluid and immunoglobulin levels. These data support the concept of local production of immunoglobulins by plasma cells in the lung following antigen exposure in susceptible individuals.

Murine hypersensitivity pneumonitis: evidences for the role of eicosanoids and platelet activating factor

Eicosanoids and platelet activating factor (PAF) are involved in numerous lung diseases. However, few studies have looked for their role in hypersensitivity pneumonitis (HP). HP was induced in mice by repeated instillations of Saccharapolyspora rectivirgula (Micropolyspora faeni) during 3 weeks. Bronchoalveolar lavages (BAL) were performed each week. BAL macrophage, lymphocyte and neutrophil counts increased at week 1, for a maximal increase after 3 weeks. Production of LTB4, LTC4, PGE2 and TXB2 by alveolar macrophages stimulated in vitro with calcium ionophore was maximal after 3 weeks, the appearance of PGE2 and TXB2 preceding that of LTB4 and LTC4. Eicosanoid production by AM correlated with BAL cell counts. To look for the importance of PAF in the development of experimental HP, mice were treated with BN52021 and BN50730, two PAF antagonists, and BAL were performed after 3 weeks of treatment. The compounds BN52021 and BN50730 reduced total BAL cell counts (x 10(5) cells/ml) in animals treated with S. rectivirgula from 8.4 +/- 0.8 to 4.4 +/- 1.1 and 3.7 +/- 0.2 respectively. BAL cell numbers in control animals were 0.4 +/- 0.1. In conclusion, eicosanoids are increased in experimental HP, and, as PAF, could play a role in the accumulation of alveolar cells.

Differential diagnostic value of plasma cells in bronchoalveolar lavage fluid

The aim of this study was to investigate whether the demonstration of plasma cells (PC), which are normally absent in bronchoalveolar lavage (BAL) fluid, facilitates differentiation among pulmonary disorders. Initial BAL fluid samples of 1,260 patients were analyzed. In 83 of these, PC were found. Of these 83, 47 were obtained from individuals suffering from extrinsic allergic alveolitis (EAA). The number of PC in BAL fluid from EAA patients was found related to the time between antigen exposure and BAL. Drug-induced pneumonitis appeared to be another disorder with a high percentage of cases with PC in the BAL fluid (35.7 percent). Therefore, we conclude that determination of PC in BAL fluid has differential diagnostic value in discriminating among interstitial lung diseases of various origins. However, the exact role of BAL fluid and PC and the link to clinical manifestations of these diseases needs further investigation.

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)

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)

Immunophenotyping of lymphocyte subsets in bronchoalveolar lavage fluid. Comparison of flow cytometric and immunocytochemical techniques

In order to compare flow cytometry with the conventional peroxidase anti-peroxidase method for the immunophenotyping of bronchoalveolar lavage fluid (BALF) lymphocytes, we studied BALF samples from 27 patients with various interstitial lung diseases. The results achieved with both methods were consistent concerning CD3+ pan T cells, CD4+ T helper/inducer, CD8+ T suppressor/cytotoxic and CD57+ natural killer cells. In contrast, a statistically significant lower anti-HLA-DR positive subset was obtained with flow cytometry than with the immunoperoxidase method (p less than 0.005). Since regression analyses and reliability counts showed further agreement between the methods, we conclude that flow cytometric immunophenotyping of BALF lymphocytes leads to similar, if not better, subset analyses than the immunoperoxidase method.

Experimental hypersensitivity pneumonitis in the rat: histopathology and T-cell subset compartmentalization

The pathogenesis of hypersensitivity pneumonitis (HP) appears to depend largely on T-cell specificity and interactions with monocytes/macrophages. We studied T-cell subset populations, defined by surface membrane markers with putative functional correlates, present in lung parenchyma and bronchoalveolar spaces of sensitized LEW rats following acute and chronic inhalational challenges with antigen. Our initial hypothesis was that the CD4+ RT6- (TDH) subset, the effector cell of delayed hypersensitivity, would dominate in HP lesions and that CD8+ RT6+ (TS) or CD8+ CD45R+ (TS) subsets, constituting putative suppressor T-cell populations, would dominate in lungs of animals with resolving lesions. We found, however, a heterogeneous population involving all eight of the T-cell subsets that were evaluated. Percentages of the RT6+ phenotype diminished as T cells moved from peripheral blood to lung. Dominant numbers of T cells in acute HP included CD8+ RT6- (TCYT) and CD8+ CD45R- (TCYT) subsets, with putative cytotoxic T-cell activity, in addition to CD4+ RT6- (TDH) cells. We did not demonstrate increases in T suppressor cells as the disease waned.

Recent advances in pathogenesis of allergic alveolitis

The animal-model studies discussed above appear to suggest that AA develops as the result of a complex series of immunologically specific events, involving initial sensitization, and the development of granulomatous inflammatory response by a series of genetically determined immunostimulatory events. Modulation of experimental granulomatous lesions by several of the means previously discussed may offer some important clues to the incidence and clinical course of AA in man and to future therapy and/or prevention of the disease. For example, in the animal models discussed previously in which chronic exposure to aerosolized antigen resulted in specific 'desensitization' it is possible that such repeated challenge in man may be refined to the point of inducing similar lengthy refractory periods and a decrease in pulmonary inflammation. The demonstration that hypersensitivity-type pulmonary granulomas in mice are markedly suppressed by inhibitors possessing antilipoxygenase activity, such as nafazatrom and nordihydroguairetic acid and by cyclosporine, may also open the door to investigation of such agents in the experimental treatment of granulomatous pulmonary diseases in man. It is obvious that a better understanding of these mechanisms in man can provide important information to increase our understanding of the possible prevention, modulation, and therapy of chronic granulomatous pulmonary disease.