Pulmonary alveolar macrophages in patients with sarcoidosis and hypersensitivity pneumonitis: characterization by monoclonal antibodies

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.

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.

Cockade-Like Structures in Alveolar Macrophages in Extrinsic Allergic Alveolitis

BACKGROUND AND OBJECTIVES

In immunocytochemical preparations of bronchoalveolar lavage (BAL) cells from patients with extrinsic allergic alveolitis (EAA), we observed the presence of alveolar macrophages with cockade-like structures in their cytoplasm (cockade+ alveolar macrophages). These cockade+ alveolar macrophages may reflect a subpopulation of alveolar macrophages which may show a different predominance in various interstitial lung diseases. In this study we aimed to compare the frequency of cockade+ alveolar macrophages in patients with EAA (n = 14) with the results obtained in patients with sarcoidosis (n = 11), idiopathic interstitial pneumonia (IIP; n = 10) and control subjects (n = 8). We also investigated the expression of the transferrin receptor CD71 on cockade+ alveolar macrophages.

METHODS

In BAL fluid, the total number of cells and differential counts were determined, and immunocytologic examinations of macrophages and lymphocytes were done using monoclonal antibodies. The percentage of cockade+ alveolar macrophages was determined by counting 300 macrophages in the CD20 field of an immunocytochemical slide.

RESULTS

The percentage of cockade+ alveolar macrophages was significantly higher in the EAA group (36 +/- 9%) compared to patients with sarcoidosis (12 +/- 5%) or IIP (11 +/- 10%) and control subjects (3 +/- 1%; p < 0.001). The proportion of CD71+ alveolar macrophages was significantly lower in EAA than in the other groups (p < 0.01), and the CD71 antigen was expressed on a significantly lower proportion of cockade+ alveolar macrophages compared to cockade- alveolar macrophages in EAA (p < 0.001).

CONCLUSION

We conclude that cockade+ alveolar macrophages could play a role in the pathogenesis and differential diagnosis EAA.

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: current concepts and future questions

Hypersensitivity pneumonitis (extrinsic allergic alveolitis) caused by inhaled allergens can progress to disabling or even fatal end-stage lung disease. The only truly effective treatment is early recognition and control of exposure. Although patients produce antibody exuberantly, the immunopathogenesis involves cellular immunity--notably, CD8(+) cytotoxic lymphocytes, multinucleate giant cell granulomas, and ultimately interstitial fibrosis. Many causative agents have been recognized in occupational dusts or mists, but most current new cases arise from residential exposure to pet birds (pigeons and parakeets), contaminated humidifiers, and indoor molds. The symptoms and physical findings are nonspecific. Serum IgG containing high titers of specific antibody to the offending antigen is elevated. Pulmonary function tests show restrictive and diffusion defects with hypoxemia, especially after exercise. Occasionally, small airways disease causes obstruction. Radio-graphic changes vary according to the stage of the disease and are best evaluated by means of high-resolution computed tomography. In typical cases, the history of a known exposure and the presence of a characteristic interstitial lung disease with serologic confirmation of IgG antibody to the offending antigen suffice for diagnosis. In more obscure cases, observation of changes after a natural environmental exposure, bronchoalveolar lavage, and lung biopsy might be indicated. Among the many questions that remain are the following: What is the prevalence of hypersensitivity pneumonitis and how often is it the cause of chronic interstitial fibrosis? What is the long-term prognosis? Why do most individuals exposed to these antigens develop a vigorous antibody response whereas only a few develop the disease? How does exposure to endotoxin and cigarette smoking affect the disease? To answer these questions, standardized and validated clinical laboratory immunochemical tests are needed, in addition to a systematic approach to diagnosis, classification of disease severity, risk assessment, and management. This review is limited to the disease caused by airborne allergens and focuses on its immunopathogenesis, eliciting agents, clinical manifestations, diagnosis, management, and prognosis.

Alveolar macrophage-T cell interactions during Th1-type sarcoid inflammation

Sarcoidosis is an immunomediated, multisystem disorder of unknown cause(s) characterized by a heightened Th1 immune response that leads to an uncontrolled granuloma formation at sites of disease activity. The past few years have seen outstanding advances in the understanding of immunological and molecular events involved in the pathogenesis of this disease. The idea is that several cytokines and chemokines, which are secreted at sites of disease activity, participate in granuloma formation. This paper describes recent data that have clarified some of the events that govern the development of the hypersensitivity reaction during sarcoidosis. In particular, we will review recent evidence indicating that a complex relationship exists between the macrophage/lymphocyte cellular axis and the tissue networks of cytokines.

The kinetics of surface expression of CD11/CD18 integrins and CD54 on monocytes and macrophages

Cells of the macrophage lineage mediate extremely important normal functions of the immune system. Such functions are in part related to interactions between cell-bound LeuCAMs and their ligands. MoAb staining and flow cytometric analysis were used to follow changes in surface expression of LeuCAMs and the LFA-1 ligand CD54 during maturation of peripheral blood monocytes (BM) in vitro. Surface expression of these molecules increased on BM following isolation, the greatest increase being in CD54 and CD11c. Following an initial increase, there was a reduction in CD11a expression after 2 weeks in culture, this being greater on adherent compared with suspension-maintained cells. Expression of CD11b remained high throughout the culture period. LeuCAM and CD54 expression was further compared on freshly isolated alveolar macrophages (AM) and BM paired donors. A reciprocal relationship was observed between CD11c and CD11b on AM and BM, in that BM expressed higher levels of CD11b than CD11c, whilst the converse was true for AM. CD54 expression was also higher on AM than on BM, whilst there was no significant difference in expression of CD11a on these cells. These data suggest that consistent changes occur in the surface expression of the LeuCAMs and CD54 as monocytes mature into macrophages, which may reflect the specific functions of these cells.

Increased levels of soluble serum interleukin-2 receptor in extrinsic allergic alveolitis correlate with interleukin-2 receptor expression on alveolar macrophages

In a group of 20 patients with extrinsic allergic alveolitis (10 with farmer's lung, 9 with bird-breeder's lung, and 1 with humidifier's lung), we observed increased levels of soluble serum interleukin-2 receptor (ssIL-2R) with an average of 75.2 pmol (control group average, 40.6 pmol). Analysis of bronchoalveolar lavage cells by immunocytochemistry with a CD25 antibody revealed only a slight increase to 4.2% IL-2R+ cells among alveolar lymphocytes but a pronounced rise to 21.2% IL-2R+ cells among alveolar macrophages. Furthermore, cytometry revealed a fourfold higher IL-2R expression on a per cell basis for alveolar macrophages as compared with alveolar lymphocytes. A clear-cut positive correlation (p = 0.006) was found for ssIL-2R and IL-2R+ alveolar macrophages, but only a borderline correlation was found for ssIL-2R and IL-2R+ alveolar lymphocytes (p = 0.04). The finding of a concomitant decrease of IL-2R+ alveolar macrophages and of ssIL-2R on allergen avoidance further supports the notion that alveolar macrophages may be the main source of the increased ssIL-2R in patients with extrinsic allergic alveolitis.

Southwestern internal medicine conference: sarcoidosis: immunology and clinical management

Sarcoidosis is a chronic inflammatory disease characterized by the presence of noncaseating granulomas in the lung and other organs. Current evidence suggests that this response is driven by a foreign antigen whose identity remains unclear. In this article, the nature of the cellular immune response is explored and the value of local markers of inflammation in predicting clinical course is examined.

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)

Concomitant modulation of serum-soluble interleukin-2 receptor and alveolar macrophage interleukin-2 receptor in sarcoidosis

Interleukin-2 receptor (IL-2R) expression on bronchoalveolar lavage (BAL) cells was studied in patients with sarcoidosis using immune cytochemistry and cytometric analysis. A low percentage of alveolar lymphocytes (AL) was found positive for IL-2R, with 7% in patients with impaired lung function and 6% in patients with normal lung function (0.4% in control subjects). Expression of IL-2R on alveolar macrophages (AM) was considerably higher, with 25% in patients with lung function impairment compared with 14% in patients without lung function impairment (1.5% in control subjects). Serum-soluble IL-2R (ssIL-2R) was significantly elevated only in patients with impaired lung function (140.0 pM), but not in patients with normal lung function (52.2 pM; control subjects, 40.0 pM). These elevated levels of ssIL-2R positively correlated with the percentage of IL-2R positive AM (p < 0.001). Immunosuppressive treatment in three patients resulted in a decrease of IL-2R+ AM and in a decrease of ssIL-2R, whereas IL-2R+ AL were unaffected. The positive correlation and the concomitant decrease of IL-2R+ AM and ssIL-2R are consistent with the idea that in sarcoidosis with clinically apparent lung involvement, elevated levels of ssIL-2R may be derived from AM and may thus be a useful indicator of the degree of activation of these cells.

Normal and sarcoid alveolar macrophages differ in their ability to present antigen and to cluster with autologous lymphocytes

Human bronchoalveolar macrophages from normal individuals function poorly as accessory cells for the presentation of common recall antigens. In sarcoidosis, alveolar macrophages (AM) are reported to be effective accessory cells for the presentation of such antigens. In this study normal and sarcoid AM were compared with blood monocytes for their ability to act as accessory cells in presenting tuberculin purified protein derivative (PPD) and streptokinase-streptodornase (SKSD) to autologous T lymphocytes, or to form spontaneous, antigen- or mitogen-induced clusters with the T cells. When compared to autologous monocytes, normal AM failed to present the two recall antigens effectively. Likewise normal AM formed very few clusters with T lymphocytes when compared to monocytes, even in the presence of antigens or the mitogen phytohaemagglutinin (PHA). In contrast, sarcoid AM presented both antigens as effectively, and were equally effective as monocytes in forming clusters with T lymphocytes, spontaneously and in further response to antigen or mitogen. The results suggest that in sarcoidosis enhanced accessory cell function and enhanced cluster formation may be related features of bronchoalveolar macrophage populations.

Alveolar macrophages from patients with bronchogenic carcinoma and sarcoidosis similarly express monocyte antigens

It has been shown that bronchoalveolar lavages (BALs) from patients with sarcoidosis and other interstitial lung diseases contain abnormally increased numbers of alveolar macrophages (AM) expressing antigens found on monocytes. The aim of this study was to compare the phenotype of AM from patients with sarcoidosis with those from patients with non-interstitial lung disease, namely carcinoma. Using a panel of monoclonal antibodies against cells of the mononuclear phagocytic series and immunohistochemical staining, we have compared the expression of antigens on AM recovered at BAL and peripheral blood monocytes from patients with sarcoidosis, with similar cell preparations from bronchogenic carcinoma patients and normal volunteers. We have shown that CD14, CR1 (CD35) and CR3 (CD11b, CD18) are expressed on the majority of monocytes from all subjects, but on only a minority of normal AM. In both patients with sarcoidosis and patients with bronchogenic carcinoma increased proportions of AM expressed these monocyte-associated antigens. Since BALs from the carcinoma patients were derived from lung lobes which were radiologically free of tumour, the accumulation of AM expressing monocytic antigens is not a local response to the tumour. We conclude that infiltration of the lung with monocytes is a more general response to lung disease than has hitherto been reported.

Production of H2O2 by alveolar macrophages in experimental allergic alveolitis

Experimental extrinsic allergic alveolitis (EAA) was induced in guinea pigs with Saccharopolyspora rectivirgula. Bronchoalveolar lavages were performed before inducing EAA (day 1, BAL 1), on day 23 (BAL 2), and on day 48 (BAL 3). The number of cells/ml in lavage fluid was increased at BAL 2 (4.79 x 10(6) and BAL 3 (4.29 x 10(6)) compared with BAL 1 (0.56 x 10(6)). The number of major cell types increased simultaneously, neutrophil becoming the predominant cell type over alveolar macrophages (AM). The production of H2O2 by AM was measured at the different phases of EAA. Adherent AM were either non-stimulated or triggered with phorbol myristate acetate (PMA), zymosan. S. rectivirgula opsonized with normal guinea pig serum (SRNS), or S. rectivirgula opsonized with guinea pig anti-S, rectivirgula serum (SRAS). Stimulated AM produced larger quantities of H2O2 than unstimulated cells, PMA being the most potent stimulus. At day 1, AM stimulated with S. rectivirgula and zymosan produced similar quantities of H2O2. After the induction of the disease, AM stimulated with S. rectivirgula produced larger quantities of H2O2 than with zymosan. Production of H2O2 by AM stimulated with S. rectivirgula or PMA, respectively, stayed the same at day 1 and 23, but increased sharply for both stimuli at day 48. There was no difference between H2O2 production by AM triggered with SRNS or with SRAS.(ABSTRACT TRUNCATED AT 250 WORDS)

Increases in HLA-DQ, DP, DR, and transferrin receptors on alveolar macrophages in sarcoidosis and allergic alveolitis compared with fibrosing alveolitis

We have used flow cytometric methods to detect and quantify HLA-DR, DQ, and DP antigens and transferrin receptors on alveolar macrophages in lavage samples from 36 patients with granulomatous lung diseases (extrinsic allergic alveolitis [EAA], n = 13; sarcoidosis, n = 23), and 12 patients having fibrosing alveolitis (FA) (cryptogenic fibrosing alveolitis, n = 3; FA and scleroderma, n = 8; FA and primary biliary cirrhosis, n = 1). HLA-DR, DQ, and DP antigens were expressed on the majority of alveolar macrophages in all the patients, and the percentages of positive cells were similar to those in control subjects without lung disease. However, the amounts expressed were higher in those with EAA and sarcoidosis than in the FA group or control subjects, the most significant differences being in HLA-DQ and HLA-DP expression. Transferrin receptor expression was also higher in the granulomatous lung diseases. In sarcoidosis, higher levels of HLA-DQ correlated with lower lung function measurements (Dco p less than 0.025, FVC p less than 0.025, FEV1 p less than 0.005), suggesting this may be a marker of disease activity. HLA-DP levels also showed a trend (p less than 0.1) of inverse correlation with lung function. Levels of HLA-DQ (p less than 0.005) and HLA-DP (p less than 0.001) correlated more closely than HLA-DR with numbers of lymphocytes in the lavage fluids, and HLA-DQ levels correlated with increasing proportions of lymphocytes in proliferation (p less than 0.05). We suggest that high levels of HLA-DQ and DP on alveolar macrophages may be more relevant than HLA-DR to the enhanced antigen-presenting function of these cells in sarcoidosis, and possibly also in EAA.

Pulmonary alveolar macrophages from patients with active sarcoidosis express type IV collagenolytic proteinase. An enzymatic mechanism for influx of mononuclear phagocytes at sites of disease activity

Alveolar macrophages (AMs) recovered from the bronchoalveolar lavage (BAL) of 44 patients with sarcoidosis were evaluated for their ability to release type IV collagenolytic metalloproteinase (IV-Case). This enzyme, which is produced by peripheral blood monocytes (PBMs) but not by tissue macrophages, degrades type IV collagen, the major structural component of vessel wall basement membranes, and helps to promote the migration of PBMs from the blood compartment to peripheral tissues. Our results demonstrated that AMs from patients with active sarcoidosis released significantly increased levels of IV-Case with respect to patients with inactive disease and control subjects. After in vitro culture, sarcoid AMs secreted IV-Case during the first 24 h of collection; after that time, AMs progressively lost their ability to release IV-Case. Exposition of both sarcoid and normal AMs to recombinant IL 2 or gamma IFN did not influence their property to release IV-Case. The immunoblot analysis of IV-Case demonstrated complete identity between IV-Case released by AMs and the degradative enzyme obtained from PBMs. The increased property to release IV-Case was significantly related to the increase of the absolute number of AMs and, in particular, of AMs bearing two determinants that are usually expressed by most PBMs (CD11b and CD14). Selective depletion of CD11b+/CD14+ AMs from the entire macrophagic population was associated with the recovery of the IV-Case activity to normal values. A positive correlation was also found between the increase in the absolute number of lung T cells and the enhanced CD4/CD8 pulmonary ratio. A 6-mo follow-up study indicated a significant association between the positivity for the 67Gallium scan and the increased property of AMs to release IV-Case. Our data are consistent with the hypothesis that a IV-Case mediated influx of peripheral monocytes takes place in the lung of sarcoid patients. Furthermore, the correlation found between the IV-Case release and disease activity suggests that this assay could represent a useful tool in sarcoidosis disease staging.