Alveolitis In Pulmonary Sarcoidosis Research Articles

Localization of the immune response in sarcoidosis.

Pulmonary sarcoidosis is an interstitial disease characterized by granulomas within the lung parenchyma, anergy to a variety of skin tests, and decreased numbers of circulating T-lymphocytes. To evaluate the effector cell populations present at sites of disease in patients with active pulmonary sarcoidosis, inflammatory and immune effector cells were isolated from lung via bronchoalveolar lavage and compared to comparable cell populations from the peripheral blood of the same patients and similar cell populations of normal subjects and patients with idiopathic pulmonary fibrosis. Patients with sarcoidosis had a marked increase in the percentage of T-lymphocytes in the lung despite a significant peripheral blood T-lymphocytopenia. In addition, many of these T-lymphocytes demonstrated surface marker characteristics associated with lymphocyte activation, and they spontaneously secreted leukocyte inhibitory factor. In contrast to patients with sarcoidosis, normal subjects and patients with idiopathic pulmonary fibrosis had similar percentages of T-lymphocytes in lung and blood, and there was no evidence for T-lymphocyte activation. Analysis of lymphocytes in uninvolved marrow from 7 of 8 patients with sarcoidosis revealed proportions of T-lymphocytes similar to those in the marrows of normal subjects and patients with idiopathic pulmonary fibrosis. In comparison, one patient with sarcoidosis had large numbers of T-lymphocytes in bone marrow, but only in areas where there were granulomas in the marrow. These studies suggest that: (1) the alveolitis of pulmonary sarcoidosis is characterized by large numbers of activated T-lymphocytes, and (2) there is an anatomic localization of the immune response in sarcoidosis in that analysis of uninvolved tissues such as peripheral blood may not reflect local immune responses at sites of granuloma formation.

Comparative Evaluation of Serum Markers in Pulmonary Sarcoidosis

Although several serum markers have shown their ability to reflect lymphocytic alveolitis and disease progression in pulmonary sarcoidosis, to our knowledge no prior study has made comparative evaluations of these markers. Forty-three patients with pulmonary sarcoidosis were enrolled. BAL fluid (BALF) cells were analyzed, and serum levels of serum amyloid A (SAA), soluble interleukin 2 receptor (sIL-2R), lysozyme, angiotensin-converting enzyme (ACE), and the mucin-like, high-molecular-weight glycoprotein KL-6 were measured at disease presentation. Clinical data, including chest radiographs, were collected at presentation and during follow-ups. Univariate and multivariate analyses were used to identify markers best predictive of increased parenchymal infiltration. Significantly higher serum levels of sIL-2R, lysozyme, and KL-6 were found in patients with parenchymal infiltration compared with those without parenchymal infiltration. The numbers of total cells and lymphocytes in BALF were significantly higher in patients with parenchymal infiltration. Serum levels of sIL-2R, lysozyme, and KL-6 were significantly correlated with the numbers of total cells, lymphocytes, and CD4(+) T lymphocytes in BALF. At the cutoff levels determined by receiver operating characteristic curves, sIL-2R, lysozyme, KL-6 serum levels, and the number of BAL lymphocytes showed significant correlations with increased parenchymal infiltrations by univariate analysis. However, multivariate analysis revealed that only KL-6 was a predictor of increased parenchymal infiltration. Our results suggest that initial serum sIL-2R, lysozyme, and KL-6 levels may reflect lymphocytic alveolitis in pulmonary sarcoidosis. Furthermore, initial serum KL-6 tends to associate with increased parenchymal infiltration in pulmonary sarcoidosis.

CC and C chemokine expression in pulmonary sarcoidosis.

The chemokines RANTES (regulated on activation, T-cell expressed and secreted; CC chemokine ligand (CCL)-5) and monocyte inflammatory protein (MIP)-1alpha (CCL-3) have been implicated in the development of alveolitis in pulmonary sarcoidosis. The novel C chemokine single cysteine motif (SCM)-1alpha (XCL-1) and the CC chemokine monocyte chemoattractant protein (MCP)-1 (CCL-2) are also mononuclear-cell attractants and represent alternative candidate mediators of alveolitis. Therefore, the expression of MCP-1 and SCM-1alpha was investigated together with the expression of RANTES and MIP-1alpha in bronchoalveolar lavage fluid (BALF) from control subjects and patients with sarcoidosis. The relationship between chemokine expression and sarcoidosis clinical course was also explored. Messenger ribonucleic acid (mRNA) expression for all four chemokines was determined by semiquantitative reverse transcriptase-polymerase chain reaction of RNA extracted from unseparated bronchoalveolar cells (17 patients, 12 controls). RANTES, MIP-1alpha and MCP-1 proteins were measured by enzyme-linked immunosorbent assay of unconcentrated BALF (60 patients, 17 controls). MCP-1, and namely RANTES and SCM-1alpha mRNA expression was upregulated in sarcoidosis, particularly in patients with more advanced disease. RANTES, and namely MCP-1 concentrations were elevated in BALF samples obtained from patients; MCP-1 levels were most increased in patients with chest radiographic stage 2 disease and also in patients with persistent and recurrent disease. In conclusion, chemokines monocyte chemotactive protein-1 and single cysteine motif-1alpha are, in addition to RANTES, associated with the development of alveolitis in sarcoidosis and their expression parallels the disease course.

Role of IL-15, IL-2, and their receptors in the development of T cell alveolitis in pulmonary sarcoidosis.

Recent data suggest that the newly discovered cytokine IL-15 cooperates with IL-2 in driving T cell-mediated immune responses. The aim of this study was to determine the role of IL-15 in the regulatory networks leading to the development of T cell alveolitis in the lung of patients with sarcoidosis. We demonstrated that alveolar macrophages (AMs) isolated from the bronchoalveolar lavage of patients with active sarcoidosis expressed IL-15 mRNA and membrane and cytoplasmic IL-15, while AMs from healthy subjects and patients with inactive sarcoidosis did not. Pulmonary CD4+ T cells from sarcoid patients were equipped with the IL-2R subunits, which are able to bind IL-15, i.e., the IL-2R beta/IL-2R gamma complex, and proliferated in response to IL-15. Interestingly, the T cell proliferation elicited by IL-15 was comparable with that determined by IL-2. Following the addition of graded amounts of IL-15, IL-2-pulsed T cells showed a significant increase in their stimulation. TNF-alpha up-regulated the IL-15-mediated proliferative response of bronchoalveolar lavage T lymphocytes. Following the block of the IL-2R beta- and gamma-chains with specific mAbs, the stimulatory activity of IL-15 was abolished. The evaluation of the IL-2R on sarcoid AMs demonstrated the constitutive expression of alpha- and gamma-chain mRNA and proteins. Taken together, these findings demonstrate that IL-15 triggers the growth of sarcoid T cells through the IL-2R beta/IL-2R-gamma complex and raise the possibility that AMs may deliver proliferative signals for the development of the T cell alveolitis. Modulation of IL-2R on AMs could represent a critical variable in regulating local inflammatory responses.

Intercellular adhesion molecule 1 (ICAM-1) in the pathogenesis of mononuclear cell alveolitis in pulmonary sarcoidosis.

Alveolitis in pulmonary sarcoidosis is characterised by an accumulation of highly activated macrophages and CD4+ lymphocytes in the alveolar compartment. The role of intercellular adhesion molecule 1 (ICAM-1) expression on alveolar cells has been studied in this context. Using a sandwich ELISA technique, ICAM-1 expression on alveolar macrophages from 17 consecutive untreated patients with pulmonary sarcoidosis and six healthy normal volunteers was quantified. In addition, parameters of macrophage activation (tumour necrosis factor alpha (TNF alpha) and superoxide anion release) were evaluated. Significantly elevated expression could be demonstrated on alveolar macrophages from patients with pulmonary sarcoidosis compared with healthy controls (mean (SD) 0.74 (0.24) ELISA units (EU) v 0.46 (0.12) EU). On subdividing the patients into those with active and those with inactive disease, only the former showed increased ICAM-1 levels on alveolar macrophages (0.82 (0.27) EU) compared with control alveolar macrophages. No differences were detected in serum levels of soluble ICAM-1 between patients and controls. ICAM-1 expression on alveolar macrophages from patients with sarcoidosis correlated with the spontaneous release of TNF alpha but not with the release of the superoxide anion by the activated macrophages. There was no correlation with the percentage of lymphocytes or the absolute number of CD4+ cells in bronchoalveolar lavage fluid. Increased ICAM-1 surface expression on alveolar macrophages reflects disease activity in the pulmonary compartment. Considering the significance of adhesion molecules during antigen presentation and lymphocyte activation, ICAM-1 expression on alveolar macrophages may have an important role in the immune process of pulmonary sarcoidosis.

Semi-quantitative gallium-67 lung scanning as a measure of the intensity of alveolitis in pulmonary sarcoidosis.

Gallium-67 (67Ga) lung scanning has been applied for some years in pulmonary sarcoidosis to assess the activity of the alveolitis. Interpreting the scans, however, is difficult due to the low uptake of 67Ga in the disease process relative to background activity. In this study we have measured the mean parenchymal lung activity of 67Ga and have compared the lung activity to that at three remote sites, the liver, the abdomen and the thigh. The results obtained were compared with the percentage of lymphocytes in broncho-alveolar lavage fluid. There was a very good correlation with the lung-to-thigh uptake measurements and a much poorer correlation with the lung-to-liver and the lung-to-abdomen measurements. It was observed that steroid therapy reduced dramatically the correlation between the broncho-alveolar lavage findings and the 67Ga scan measurements. The results suggest that in patients not on steroid therapy, the 67Ga lung-to-thigh measurements may be used, similarly to the broncho-alveolar lavage lymphocyte counts, to identify those with high-intensity alveolitis from those with low-intensity alveolitis.

Suppression of the alveolitis in pulmonary sarcoidosis by oral corticosteroids.

We evaluated the effects of daily prednisone therapy on alveolitis parameters and pulmonary function tests over a six month period in patients with active pulmonary sarcoidosis (>28% T lymphocytes in bronchoalveolar lavage and positive gallium-67 (67Ga) lung scans). 10 patients with biopsyproven lung disease were studied. Analysis of bronchoalveolar lavage cells and of67Ga scanning at the beginning and at the end of the study period demonstrated that prednisone treatment significantly lowered the percentages of T lymphocytes in bronchoalveolar lavage in all patients (baseline 48±3%, after treatment 19±5%, p<0.01) while67Ga lung scans improved in 8 of the 10 patients. Pulmonary function tests showed improvement of the parameters studied (+7.5±2.1% mean change in vital capacity, +4.7±1.6% mean change in total lung capacity, +5.4±2% mean change in forced expiratory volume in one second and +6.2±1.5% mean change in diffusing capacity). In addition none of the treated patients deteriorated functionally and 9 of the 10 patients improved more than 10% in at least one parameter.

An in vitro gallium-67 lung index for the evaluation of sarcoidosis.

In the evaluation of the active alveolitis of pulmonary sarcoidosis, both the proportional lymphocyte count obtained by bronchoalveolar lavage and state of activation of the alveolar macrophage by gallium scanning are required. We injected 6 mCi (200 MBq) of 67Ga intravenously on 24 occasions in 13 patients with biopsy-proved sarcoidosis. Forty-eight hours later, patients were scanned with a rectilinear scanner and the generated scintigrams were evaluated using the NIH index. Seventy-two hours after injection, bronchoalveolar lavage was performed, and venous blood was sampled. The harvested lavage fluid was analyzed for absolute and proportional cell counts, and radioactivity was measured in blood and BAL fluid. An in vitro 67Ga index was generated and expressed as counts/100,000 alveolar macrophages/ml blood (mean, 0.0146 +/- 0.0087 SD). There was a significant relationship between the in vitro index and proportional lymphocyte BAL counts (r = 0.79; p less than 0.002) that was comparable to that obtained using the NIH index (r = 0.74; p less than 0.005). These data suggest that the in vitro index might offer a more objective assessment of 67Ga uptake by the lung, but this would require validation against clinical parameters in a prospective study.

NIH conference. Pulmonary sarcoidosis: a disease characterized and perpetuated by activated lung T-lymphocytes.

The alveolitis of pulmonary sarcoidosis is characterized by an intense, mononuclear cell infiltrate that probably precedes granuloma formation. Pathogenic mechanisms underlying pulmonary sarcoidosis can be shown by study of the mononuclear cells composing the alveolitis. Bronchoalveolar lavage has shown that the sarcoid lung is characterized by increased numbers of "activated" T-lymphocytes within the alveolar structures. In contrast to normal control cells, the lung T-lymphocytes of patients with sarcoid release the mediator, monocyte chemotactic factor, that probably contributes to the pathogenesis of sarcoidosis by recruiting blood monocytes to the lung, thus providing cellular building blocks for granuloma formation. Conventional monitors of the activity of pulmonary sarcoidosis, such as blood studies, pulmonary function testing, and chest roentgenograms, show little assessed by bronchoalveolar lavage or by histopathologic studies. In contrast, quantification of lavage T-lymphocyte populations and 67Ga scintigraphy of the chest provide a sensitive and specific means of assessing the activity of the alveolitis in pulmonary sarcoidosis and may provide a rational basis for therapy.