Increased expression of leukocyte function associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) by alveolar macrophages of patients with pulmonary sarcoidosis

Recent advances in understanding the biomolecular basis of chronic beryllium disease: a review

In this review we summarize the work conducted over the past decade that has advanced our knowledge of pulmonary diseases associated with exposure to beryllium that has provided a molecular-based understanding of the chemistry, immunopathology, and immunogenetics of beryllium toxicity. Beryllium is a strong and lightweight metal that generates and reflects neutrons, resists corrosion, is transparent to X-rays, and conducts electricity. Beryllium is one of the most toxic elements on the periodic table, eliciting in susceptible humans (a) an allergic immune response known as beryllium sensitization (BeS); (b) acute beryllium disease, an acutely toxic, pneumonitis-like lung condition resulting from exposure to high beryllium concentrations that are rarely seen in modern industry; and (c) chronic beryllium disease (CBD) following either high or very low levels of exposure. Because of its exceptional strength, stability, and heat-absorbing capability, beryllium is used in many important technologies in the modern world. In the early 1940s, beryllium was recognized as posing an occupational hazard in manufacturing and production settings. Although acute beryllium disease is now rare, beryllium is an insidious poison with a latent toxicity and the risk of developing CBD persists. Chronic beryllium disease-a systemic granulomatous lung disorder caused by a specific delayed immune response to beryllium within a few months to several decades after exposure-has been called the "unrecognized epidemic". Although not a disease in itself, BeS, the innate immune response to beryllium identified by an abnormal beryllium lymphocyte proliferation test result, is a population-based predictor of CBD. Genetic susceptibility to CBD is associated with alleles of the major histocompatibility gene, human leukocyte antigen DP (HLA-DP) containing glutamic acid at the 69th position of the beta chain (HLA-DPbeta-E69). Other genes are likely to be involved in the disease process, and research on this issue is in progress. The current Occupational Safety & Health Administration permissible exposure limit of 2 microg/m3 has failed to protect workers from BeS/CBD. As a safe exposure limit that will not lead to BeS or CBD has not yet been determined, the realization that the risk of CBD persists has led to a renaissance in research on the effects of the metal on human health. Current data support further reductions in exposure levels to help minimize the incidence of CBD. Steps that would directly impact both the power of epidemiologic studies and the cost of surveillance would be to develop and validate improved screening and diagnostic tests, and to identify more genetic factors that affect either sensitization or disease process. The major focus of this review is the recent research on the cellular and molecular basis of beryllium sensitization and disease, using a multidisciplinary approach of bioinorganic chemistry and immunology. First we present a historical background of beryllium exposure and disease, followed by occurrence of beryllium in the environment, toxicokinetics, biological effects, beryllium lung disease, and other human health effects.

Circulating CD14+ CD16+ monocytes are expanded in sarcoidosis patients

Sarcoidosis is a systemic disease of unknown etiology characterized by noncaseating granulomas, consisting mainly of epithelioid cells and multinucleated giant cells derived from monocyte-macrophage lineage cells. Monocytes fall into subpopulations comprising CD14++ CD16-, and CD14+ CD16+ cells, and expansion of the later monocytes has been reported under some pathological conditions. In this study, we examined the immunophenotype of blood monocytes in patients with sarcoidosis using two-color immunofluorescence flow cytometry. In healthy controls CD14+ CD16+ monocytes account for 5.8 +/- 2.8% of monocytes. The percentage of CD14+ CD16+ monocytes was significantly higher (p <0.02) in the sarcoidosis patients (11.8 +/- 4.9%) compared with those in healthy control subjects. The serum ACE levels were significantly correlated with the percentage of CD14+ CD16+ monocytes (p <0.05). In contrast, the percentage was not correlated with purinergic receptor expression of monocytes as estimated by LDH release from BzATP-stimulated monocytes. These findings suggest that CD14+ CD16+ monocytes represent a sensitive marker for the disease activity of sarcoidosis.

Monocyte-derived multinucleated giant cells and sarcoidosis

Multinucleated giant cells (MGC) are characteristic cells in granulomatous disorders such as sarcoidosis and also formed in vitro from peripheral blood mononuclear cells by stimulation with cytokines, including interferon-gamma (IFN-gamma), interleukin-3 (IL-3), IL-4, IL-13, and granulocyte-macrophage-colony stimulating factor. In addition to such inflammatory mediators, a factor derived from the pathogens of granulomatous disorders may be necessary for MGC formation. Muramyl dipeptide (MDP), a peptidoglycan portion of bacterial cell walls present in sarcoidal lesions, is one of the candidates and can preferentially induce Langhans-type cells (LGC) in in vitro MGC formation system. Although the exact mechanisms of in vitro MGC formation remains unknown, receptors such as P2X(7), integrins, CD98, and macrophage fusion protein are considered to be involved in cell-to-cell adhesion and subsequent fusion process. Monocytes from sarcoidosis patients expressed higher levels of P2X(7) and had a higher ability to induce MGC than those from healthy controls. Attributable cells for the formation were CD14(++)CD16(-) monocytes. Therefore, CD14(++)CD16(-) monocytes may infiltrate into sarcoidal lesions and be fused to form LGC by inflammatory mediators and MDP derived from the pathogens of the disorder. Effective agents for sarcoidosis such as tranilast, allopurinol, and captopril inhibited in vitro MGC formation through inhibiting the expression of adhesion molecule and purinergic receptor. Thus, an in vitro MGC formation model would be a useful tool to understand the relevance of MGC in granulomatous disorders.

Role of ICAM-1 in the aggregation and adhesion of human alveolar macrophages in response to TNF-alpha and INF-gamma

Intracellular adhesion molecule-1 (ICAM-1)-mediated cell-cell adhesion is thought to play an important role at sites of inflammation. Recent evidence suggests that ICAM-1 surface expression on alveolar macrophages is increased in pulmonary sarcoidosis and that inflammatory granuloma formation is characterized by the aggregation of macrophages. The present study shows that ICAM-1 expression is significantly elevated on alveolar macrophages from patients with sarcoidosis in response to tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (INF-gamma) compared with healthy controls. Aggregation and adhesion were significantly increased in alveolar macrophages treated with TNF-alpha and INF-gamma, and significantly inhibited in those pretreated with a monoclonal antibody to ICAM-1. Similarly, aggregation and adhesion were inhibited in macrophages treated with heparin, which then exhibited a wide range of biological activities relevant to inflammation. These results suggested that the surface expression of ICAM-1 on alveolar macrophages in response to TNF-alpha and INF-gamma is important in mediating aggregation and adhesion. Additionally, heparin may be useful for developing novel therapeutic agents for fibrotic lung disease.

Heightened ability of monocytes from sarcoidosis patients to form multi-nucleated giant cells in vitro by supernatants of concanavalin A-stimulated mononuclear cells

The main immunocompetent cells in sarcoidal lesions are epithelioid cells and multi-nucleated giant cells (MGC), both of which are derived from monocyte-macrophage lineage cells. To understand further the relevance of monocytes in sarcoidosis, we examined in vitro MGC formation using monocytes from sarcoidosis patients, patients with other granulomatous diseases (OGD) and healthy control subjects. The supernatant of concanavalin A-stimulated peripheral blood mononuclear cells (conditioned medium) generated Langhans type-MGC and foreign body type-MGC from monocytes. Conditioned medium from any three groups had the same ability to form MGC from normal monocytes. On the other hand, MGC were more highly formed using monocytes from sarcoidosis patients than from other groups. When macrophages induced by treatment of monocytes with macrophage colony-stimulating factor (M-CSF) were used, the rate of MGC formation in sarcoidosis patients was about threefold or fourfold as much as that in OGD patients or healthy controls, respectively. Oxidized ATP inhibited MGC formation in all groups. The susceptibility of monocytes cultured in conditioned medium for 24 h to 2'- and 3'-o-(4-benzoyl-benzoyl)ATP-mediated cytolysis was significantly higher in sarcoidosis patients than other groups. These findings suggest that the ability of monocytes to form MGC through P2x7 receptors is enhanced in sarcoidosis patients.

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.

Phenotypic analysis of lymphocytes and monocytes/macrophages in peripheral blood and bronchoalveolar lavage fluid from patients with pulmonary sarcoidosis

BACKGROUND

The granulomatous inflammation in sarcoidosis is driven by the interplay between T cells and macrophages. To gain a better understanding of this process the expression by these cells of cell surface activation markers, co-stimulatory molecules, and adhesion molecules was analysed.

METHODS

CD4+ and CD8+ T lymphocytes from peripheral blood (PBL) or bronchoalveolar lavage (BAL) fluid, as well as paired peripheral blood monocytes and alveolar macrophages from 27 patients with sarcoidosis were analysed by flow cytometry.

RESULTS

CD26, CD54, CD69, CD95, and gp240 were all overexpressed in T cells from BAL fluid compared with those from PBL in both the CD4+ and CD8+ subsets, while CD57 was overexpressed only in BAL CD4+ cells. In contrast, CD28 tended to be underexpressed in the BAL T cells. Monocyte/macrophage markers included CD11a, CD11b, CD11c, CD14, CD16, CD54, CD71, CD80 and CD86 and HLA class II. CD11a expression in alveolar macrophages (and peripheral blood monocytes) was increased in patients with active disease and correlated positively with the percentage of BAL lymphocytes. Expression of CD80 in macrophages correlated with the BAL CD4/CD8 ratio.

CONCLUSIONS

Our data indicate substantial activation of both CD4+ and CD8+ lung T cells in sarcoidosis. There were also increased numbers of BAL lymphocytes whose phenotypic characteristics have earlier been associated with clonally expanded, replicatively senescent cells of the Th1 type.

Value of ICAM-1 expression and soluble ICAM-1 level as a marker of activity in sarcoidosis

BACKGROUND

The natural course of sarcoidosis is variable, but no single parameter has been generally accepted as a good marker for disease activity. Adhesion molecules are required for the migration of inflammatory cells; thus, they may be markers of activity in sarcoidosis.

METHODS

In 16 patients with active sarcoidosis and 11 with inactive disease (10 were male, 17 were female; mean age [-/+ SD], 39.6+/-11.0 years; mean follow-up, 21+/-16 months), the expression of adhesion molecules on cells obtained with BAL (measured by flow cytometry) and the level of soluble intercellular adhesion molecule 1 (sICAM-1) in the serum and BAL fluid (BALF) were measured at the time of diagnosis and during the follow-up. The changes in serum sICAM-1 level and ICAM-1 expression on cells obtained with BAL were compared with the clinical course of the disease.

RESULTS

In patients with active disease, the ICAM-1 on alveolar macrophage (AM) (relative linear median fluorescence intensity [RMFI], 3.21+/-1.55) and sICAM-1 levels in serum (575+/-221 ng/mL) and BALF (47.3+/-19.3 ng/mL) were higher than those for patients with inactive disease (RMFI, 1.67+/-0.66; p = 0.0034; serum, 263+/-98.5 ng/mL; p = 0.0001; BALF, 27.5+/-19.0 ng/mL; p = 0.0209). In the patients with active disease, ICAMN-1 on AM and serum sICAM-1 decreased (RMFI, 1.51+/-0.84; 284+/-118 ng/mL, respectively) after steroid therapy, but no significant change was noted in patients with inactive disease. We also found that the initial ICAM-1 on AM and serum sICAM-1 had a significant correlation with the degree of improvement in pulmonary function tests after the therapy. The disease relapsed in four patients after the discontinuation of steroids, and the serum sICAM-1 level was elevated again at the time of relapse.

CONCLUSION

Our data suggest that the serum sICAM-1 level and the ICAM-1 expression on AM may be good markers of disease activity and also a predictor of outcome in sarcoidosis.

Phenotypic and functional characterization of normal rat pleural macrophages in comparison with autologous peritoneal and alveolar macrophages

Pleural mononuclear phagocytes (PleMP) were isolated from normal rats by pleural lavage and compared with autologous peritoneal (PerMP) and bronchoalveolar mononuclear phagocytes (BAMP) isolated by peritoneal and bronchoalveolar lavage, respectively. The phagocytic activity of PleMP, PerMP, and BAMP, evaluated by testing their ability to ingest latex beads, was lower for PleMP and PerMP than for BAMP. The phenotype of PleMP, PerMP, and BAMP was characterized by immunocytochemical staining with a panel of monoclonal antibodies (mAbs). As expected, PleMP, PerMP, and BAMP did not react with OX19, OX33, ED5, MOM/3F12/F2, and anticytokeratin mAbs, specific for T lymphocytes, B lymphocytes, dendritic cells, granulocytes, and epithelial/mesothelial cells, respectively. Moreover, PleMP and PerMP populations were highly enriched with OX6-, OX42-, ED7-, and ED8-positive MP, whereas BAMP population was enriched with ED1- and ED9-positive cells. To test the ability of PleMP, PerMP, and BAMP to function as accessory cells (AC), mitomycin C-treated MP were used as stimulatory cells in mixed leukocyte reaction experiments, using allogeneic T cells as responders. 3HdTR incorporation by T cells was assessed as an index of AC function. PleMP and PerMP were more potent AC than BAMP. Moreover, when cultured together with autologous pulmonary interstitial dendritic cells, PleMP and PerMP exerted a more potent ability to stimulate T-cell proliferation than did BAMP. To investigate the capacity of MP to function as bactericidal and fungicidal cells, we tested their ability to kill Escherichia coli and Cryptococcus neoformans, respectively. PleMP and PerMP were less potent bactericidal and fungicidal cells than BAMP. The results of this study demonstrate that PleMP isolated from normal rat pleural space are functionally and phenotypically different from BAMP but similar to PerMP, and suggest that these cells might play an important role in cell-mediated immune reactions in the pleural space.

Different expression of integrins by mononuclear phagocytes in peripheral blood and bronchoalveolar lavage fluid

Alveolar macrophages (AM) originate from blood monocytes and, during the maturation process, undergo functional and morphological changes which are also reflected in their phenotypic pattern. Among the macrophage membrane antigens, adhesion molecules of the integrin family are particularly important for effector functions and cell-cell interactions. The aim of this study was to analyse the membrane expression of selected integrins by AM recovered from bronchoalveolar lavage (BAL) as compared to their precursors, peripheral blood monocytes (PBM). The cells were stained using a sensitive immunoperoxidase assay with 10 different monoclonal antibodies. The data showed a higher expression by AM than PBM of all but one of the studied adhesion molecules. The only exception was CD11b (Mac-1, CR3) which showed a higher expression in PBM than in AM. Several molecules, for example, CD49d (VLA-4), CD51 (vitronectin receptor), and CD54 (intercellular adhesion molecule-1, ICAM-1) were found to be upregulated by AM in patients with a lymphocytic pattern of BAL. In contrast, the phenotype of PBM does not show any changes in these patients. In conclusion, we have demonstrated differences in the expression of integrins between AM and PBM which can be partially responsible for some of their functional differences.

Expression and modulation of ICAM-1, TNF-alpha and RANTES in human alveolar macrophages from lung-transplant recipients in vitro

Alveolar macrophages (AMs) play a central role in pulmonary inflammation in response to local stimuli. As a model for investigating anti-inflammatory drugs, we studied the effects of the cyclohexadepsipeptide antibiotic, fusafungine, and that of the glucocorticoid dexamethasone on the expression of ICAM-1, TNF-alpha and RANTES, induced in vitro by rIFN-gamma in human AMs freshly isolated from bronchoalveolar lavage fluid (BAL) obtained in lung-transplanted patients. ICAM-1 antigen expression, induced on AMs after 24 h of culture, was significantly inhibited by fusafungine in a concentration-dependent manner, as measured by flow cytometry analysis using an anti-CD54 monoclonal antibody. TNF-alpha production, but not RANTES release (measured by ELISA), was significantly inhibited. mRNA studies, by means of polymerase chain reaction amplification of complementary deoxyribonucleic acids (RT-PCR), showed no significant modification of mRNA levels, suggesting that fusafungine acts mainly at a post-transcriptional level. In the same conditions, dexamethasone significantly inhibited the release both of TNF-alpha and RANTES by AMs, mainly acting at the mRNA level, but had no effect on ICAM-1 expression. Assessment of the cellular and molecular targets of anti-inflammatory drugs in this model of human AM activation should lead to more appropriate treatment of inflammatory process of the respiratory tract. By virtue of its anti-inflammatory effects on alveolar macrophages, combined with its antibacterial properties, fusafungine should prove particularly suitable for local treatment of bacterial infections of the respiratory tract.

Smoking alters the phenotype of macrophages in induced sputum

To investigate the effect of chronic smoke exposure on pulmonary macrophages (PM), the expression of seven different surface and intracellular molecules of PM was studied in induced sputum (IS) samples from healthy volunteers--nine smokers and seven non-smokers. Sputum was induced by inhalation of nebulized saline (3.5% NaCl). Cell viability and total cell counts (TCC) were performed immediately. Cell differentials were determined on May-Grunwald Giemsa-stained cytospin preparations. The PM were immunologically characterized by use of the following monoclonal antibodies: RFD1, RFD7, CD11b, CD54, CD68, CD71 and HLA-DR. The stainings were performed with a three-step, indirect immuno-alkaline phosphate method. Viability and TCC did not differ between the groups. Smokers had a higher percentage of macrophages (P < 0.05) and a lower proportion of neutrophils (P < 0.05). The percentage of macrophages expressing RFD1, HLA-DR, CD71 (P < 0.01 for all) and CD54 (P < 0.05) was significantly lower in smokers, whereas the remaining markers were expressed equally in the two groups. The results indicate that smoking induces a decrease in the expression by PM of surface molecules known to be associated with the antigen-presenting function.

Immunology of sarcoidosis

Because of its association with cutaneous anergy, sarcoidosis was originally viewed as a defect of cellular immunity. Supporting that misperception were early studies of peripheral blood lymphocytes that found lymphopenia and impaired lymphocyte responses to mitogens and recall antigens. The clue to a vast underlying network of complex hyperactive cellular immune functions was discovered in the paradoxical finding of in vitro spontaneous lymphoblastic transformation and lymphokine production. Subsequently, investigative focus shifted to the activated, proliferating T-helper lymphocytes, the lymphokines of which were found to function in the recruitment and retention of monocytes for granuloma development. T-helper lymphocytes also contributed to the mechanism of hypergammaglobulinemia through their influence on B cells. The most intriguing question about sarcoid immunology is the initiating factor that triggers the T-lymphocyte activation and proliferation in the first place. There is much to suggest that antigen processing and presentation launches the process. Because lymphocyte activation and proliferation antedate granuloma formation at K-S skin test sites and in the lung, we combined the harvesting technique of BAL with the K-S bioassay to show that granulomagenic antigen is being processed by monocyte-macrophages. The finding of autologous monocyte-macrophage granulomagenicity raises the distinct possibility that sarcoidosis is a unique cell-mediated type of autoimmune process. The isolation and identification of the granulomagenic factor is the exciting research frontier ahead.

Effect of cardiopulmonary bypass on cytokine release and adhesion molecule expression in alveolar macrophages. Preliminary report in six cases

Although recent studies have shown that adhesion molecules on alveolar macrophages are important in a variety of pulmonary diseases, there have been few studies on the phenotypic and functional changes of alveolar macrophages during cardiopulmonary bypass. To investigate the possible role of alveolar macrophages in activating pulmonary immunity during cardiopulmonary bypass, we measured the expression of adhesion molecules on alveolar macrophages and peripheral blood monocytes in patients undergoing cardiopulmonary bypass. Antigens were stained with monoclonal antibodies against adhesion molecules, and the expression of antigens was quantified by flow cytometry as the ratio of specific to nonspecific linear fluorescence. On alveolar macrophages obtained after the release of aortic cross-clamp, macrophages as compared with alveolar macrophages obtained before cardiopulmonary bypass, there was a significant enhancement of CD11a, CD11b, CD11c, and CD18. In addition, alveolar macrophages, but not peripheral monocytes, produced higher levels of TNF-alpha and IL-8 when they were cultured in vitro. A higher expression of CD11 and CD18 on alveolar macrophages and enhanced production of cytokines after release of the aortic cross-clamp may contribute to immune activation in lung by macrophage-lymphocyte interaction.

Shed soluble ICAM-1 molecules in bronchoalveolar lavage cell supernatants and serum of patients with pulmonary sarcoidosis

The soluble form of intercellular adhesion molecule-1 (sICAM-1) might be a serum parameter of inflammatory activity gauging cellular interactions with possible relevance in sarcoidosis. To address this question we measured sICAM-1 by enzyme-linked immunosorbent assay in serum and shedding of this molecule by bronchoalveolar lavage (BAL) cells in sarcoidosis patients (44 and 40, respectively) and in controls (10 and 19, respectively). Serum concentrations of sICAM-1 (588.3 +/- 72.2 ng/ml) and its spontaneous release by BAL cells (9.9 +/- 1.5 ng/ml) in patients with active sarcoidosis were significantly higher than in those with inactive disease or controls, although no correlation was observed. Significant correlations of sICAM-1 shedding by nonstimulated BAL cells with the serum level of neopterin and of shedding by lipopolysaccharide-stimulated BAL cells with percentage of alveolar macrophages were observed in active sarcoidosis. Kinetic cell culture experiments with peripheral blood mononuclears disclosed a rapid up-regulation of sICAM-1 shedding and tumor necrosis factor-alpha release; however, at 5 h after stimulation a dissociation of their releases was observed. sICAM-1 release was maintained over 2 days, whereas tumor necrosis factor-alpha release peaked at 5 and ceased after 43 h. These results provide evidence that circulating and BAL cell culture-derived sICAM-1 reflect the stage of sarcoid inflammation. Although sICAM-1 in BAL cell supernatants originates from alveolar macrophages; the absence of a correlation with serum sICAM-1 concentration indicates that other cells are additional sources of the circulating pool of this molecule.

Effect of antioxidants on hyperoxia-induced ICAM-1 expression in human endothelial cells

The regulating mechanism of hyperoxia-induced ICAM-1 expression has not been elucidated. We studied the effect of antioxidants, including superoxide dismutase (SOD), catalase and N-acetylcysteine (NAC), on hyperoxia-induced ICAM-1 expression in human pulmonary artery endothelial cells (HPAEC) and human umbilical vein endothelial cells (HUVEC). Cells were cultured to confluence and exposed to either hyperoxic or normoxic gas with or without various kinds of antioxidants. The levels of ICAM-1 expression in the endothelial cells and the concentrations of reduced (GSH) and oxidized glutathione (GSSG) in the media were examined by flow cytometry and by spectrophotometry, respectively. After 48-hour exposure to hyperoxia, ICAM-1 expression was increased (HPAEC; 161 +/- 21% and HUVEC; 163 +/- 16%) and total glutathione concentration in the media was decreased as compared with normoxia. SOD did not change the GSH and GSSG concentrations in the media. Catalase dose-dependently decreased the supernatant GSSG concentration in both HPAEC and HUVEC, while the GSH concentration was nearly constant. NAC dose-dependently increased the supernatant GSH concentrations in both HPAEC and HUVEC. There was no difference in the supernatant GSSG concentrations between the NAC-treated HPAEC and HUVEC. There was no difference in ICAM-1 expression in either HPAEC or HUVEC with SOD treatment. ICAM-1 expressions in 100 U/ml (236 +/- 20%) and 1,000 U/ml (315 +/- 36%) of catalase were increased in HPAEC, and that in 1,000 U/ml (440 +/- 209%) of catalase was increased in HUVEC. Five and 10 U/ml of NAC decreased ICAM-1 expression in HPAEC (141 +/- 26% and 113 +/- 11%) and HUVEC (119 +/- 23% and 106 +/- 7%), respectively. These results suggest that extracellular glutathione may play a role in regulating hyperoxia-induced ICAM-1 expression in HPAEC and HUVEC.

Increased plasma concentrations of circulating intercellular adhesion molecule-1 (cICAM-1) in patients with necrotizing pancreatitis

The intercellular adhesion molecule-1 (ICAM-1), a membrane glycoprotein, is important in the adhesion of cytokine-stimulated leukocytes to the endothelium of microvessels and their transendothelial migration. Circulating isoforms of ICAM-1 (cICAM-1) are known to be elevated in human serum as an indirect consequence of inflammatory responses. The aim of this study was to investigate whether cICAM-1 levels are elevated in patients with acute pancreatitis within 48 h of the onset of abdominal pain and whether cICAM-1 levels correlate with the severity of the tissue damage. Twenty-five consecutive patients admitted to a medical ICU had elevated cCAM-1 concentrations of 548 +/- 68 ng/ml, significantly different when compared to a control group of 18 healthy subjects (343 +/- 29; p = 0.018). According to the findings of contrast-enhanced CT or laparotomy patients were further divided in a group with acute edematous pancreatitis and a group with acute necrotizing pancreatitis. Pancreatic necrosis was associated with cICAM-1 levels of 729 +/- 106 ng/ml, significantly different from patients with mild disease (367 +/- 48) and controls (p < 0.001). Plasma cICAM-1 levels were not significantly different between healthy subjects and patients with mild pancreatitis. A significant correlation was found between cICAM-1 and C-reactive protein, an acute phase reactant and marker of necrotizing pancreatitis (r = 0.62; p < 0.01). The sensitivity and specificity for the detection of edematous or necrotizing pancreatitis of cICAM-1 plasma concentrations (cutoff point at 500 ng/ml) were 75% and 85%, respectively. These results suggest an enhanced release of ICAM-1 into plasma in the early stage of acute necrotizing pancreatitis. Leukocyte-endothelial cell adhesion may be associated with the inflammatory process of necrotizing tissue damage in acute pancreatitis. It could thus serve as a marker or predictor of a severe clinical course of pancreatitis.

Intercellular adhesion molecule-1

The intercellular adhesion molecule (ICAM) 1 is an Ig-like cell adhesion molecule expressed by several cell types, including leukocytes and endothelial cells. It can be induced in a cell-specific manner by several cytokines, for example, tumor necrosis factor-alpha, interleukin-1, and interferon-gamma, and inhibited by glucocorticoids. Its ligands are the membrane-bound integrin receptors LFA-1 and Mac-1 on leukocytes, CD43, the soluble molecule fibrinogen, the matrix factor hyaluronan, rhinoviruses, and Plasmodium falciparum malaria-infected erythrocytes. ICAM-1 expression is predominantly transcriptionally regulated. The ICAM-1 promoter contains several enhancer elements, among them a novel kappa B element which mediates effects of 12-O-tetradecanoylphorbol-13-acetate, interleukin-1, lipopolysaccharide, tumor necrosis factor-alpha, and glucocorticoids. Expression regulation is cell specific and depends on the availability of cytokine/hormone receptors, signal transduction pathways, transcription factors, and posttranscriptional modification. ICAM-1 plays a role in inflammatory processes and in the T-cell mediated host defense system. It functions as a costimulatory molecule on antigen-presenting cells to activate MHC class II restricted T-cells, and on other cell types in association with MHC class I to activate cytotoxic T-cells. ICAM-1 on endothelium plays an important role in migration of (activated) leukocytes to sites of inflammation. ICAM-1 is shed by the cell and detected in plasma as sICAM-1. Regulation and significance of sICAM-1 are as yet unclear, but sICAM-1 is increased in many pathological conditions. ICAM-1 may play a pathogenetic role in rhinovirus infections. Derangement of ICAM-1 expression probably contributes to the clinical manifestations of a variety of diseases, predominantly by interfering with normal immune function. Among these are malignancies (e.g., melanoma and lymphomas), many inflammatory disorders (e.g., asthma and autoimmune disorders), atherosclerosis, ischemia, certain neurological disorders, and allogeneic organ transplantation. Interference with ICAM-1 leukocyte interaction using mAbs, soluble ICAM-1, antisense ICAM-1 RNA, and in the case of melanoma mAb-coupled immunotoxin, may offer therapeutic possibilities in the future. Integration of knowledge concerning membrane-bound and soluble ICAM-1 into a single functional system is likely to contribute to elucidating the immunoregulatory function of ICAM-1 and its pathophysiological significance in various disease entities.

Elevated levels of soluble ICAM-1 in serum and BAL fluid in patients with active sarcoidosis

Intercellular adhesion molecule-1 (ICAM-1), a member of the immunoglobulin superfamily of adhesion molecules, plays an important role in inflammatory and immune diseases. The soluble form of ICAM-1 (sICAM-1) shed from the cell surface may be a marker of inflammatory response and may reflect the disease activity. We measured the levels of sICAM-1 in serum and bronchoalveolar lavage fluid (BALF) in patients with sarcoidosis. Healthy volunteers were examined as controls. sICAM-1 concentrations were measured using an enzyme-linked immunosorbent assay kit with two different monoclonal antibodies. Serum and BALF sICAM-1 levels in sarcoidosis were significantly higher than those in control. Serum sICAM-1 levels correlated with serum soluble interleukin-2 receptor levels (a marker of T-lymphocyte activation) but not with serum angiotensin-converting enzyme levels. sICAM-1 levels in BALF correlated significantly with the percentage of lymphocytes in BALF. Some patients were examined twice during follow-up periods. In patients in whom the chest radiograph improved, serum and BALF sICAM-1 levels decreased. However, in patients in whom the radiograph worsened, sICAM-1 levels increased. These results suggest that measurement of sICAM-1 may be useful to investigate not only the pathogenic mechanisms, but also the clinical status and disease activity in patients with sarcoidosis.

Increased expression of intercellular adhesion molecule-1 (ICAM-1) in a murine model of pulmonary eosinophilia and high IgE level

T lymphocytes and eosinophils are probably involved in the pathogenesis of allergic bronchopulmonary aspergillosis (ABPA), a disease characterized by pulmonary eosinophilia and high serum and lavage IgE levels. We recently developed a murine model of ABPA. To investigate the mechanisms of T lymphocyte and eosinophil recruitment to the lung in this disease, we examined the expression of ICAM-1 in the lung tissue of mouse challenged with Aspergillus fumigatus (Af) antigen. C57B1/6 mice were intranasally exposed to Af (Af group) or saline (control group) three times a week for 1, 2 or 3 weeks. On days 4, 7, 14 and 21, mice were killed and lung tissue was fixed in acetone and embedded in glycol methacrylate. Serial 2-microns sections were stained with chromotrope 2R and MoAbs against ICAM-1, CD11a/CD18 (LFA-1) and CD3. Af-challenged mice presented significant increases in eosinophil, T lymphocyte and LFA-1-positive cell count and up-regulated expression of ICAM-1 in the lung tissue at all the time points examined. ICAM-1 expression intensity correlated with the number of T lymphocytes (r = 0.59, P < 0.01), LFA-1-positive cells (r = 0.68, P < 0.001), but not of eosinophils (r = -0.24, P > 0.05). These findings suggest that up-regulation of ICAM-1 expression is involved in the inflammatory process of this murine model of ABPA, and that this up-regulation may be more relevant to the the T lymphocyte accumulation in the lung.

Mononuclear cells in exudative malignant pleural effusions. Characterization of pleural phagocytic cells

The aims of this study were to develop a methodology for the isolation of highly enriched mononuclear phagocyte populations from exudative malignant pleural effusions (EMPE) and to characterize the phenotype and functional properties of these cells. Pleural effusion mononuclear cells (PEMC) were isolated by Ficoll centrifugation of EMPE and transudative pleural effusions and allowed to adhere to plastic for 1 h to obtain a pleural effusion mononuclear adherent cell (PEMAC) fraction. Only 66.0 +/- 4.2 percent of PEMAC ingested latex particles, indicating that a significant proportion of PEMAC were not phagocytic cells. Latex-positive PEMAC had the morphologic appearance of macrophages and stained positive (97.3 +/- 4.3 percent) with the anti-CD68 monoclonal antibody (MoAb), specific for macrophages. Conversely, latex-negative PEMAC (34.0 +/- 4.1 percent of PEMAC) did not react with the anti-CD68 MoAb and stained with anti-CD3 (34.7 +/- 10.7 percent) and anticytokeratin (50.5 +/- 16.4 percent) MoAbs, indicating that T cells and mesothelial cells were present in the PEMAC fraction. To improve the purification of pleural macrophages, PEMAC were cultured for an additional 18 h and the cells that remained adherent after this period constituted the firmly adherent mononuclear cell (FAMC) fraction. Nearly 90 percent of FAMC ingested latex particles and were CD68-positive. Virtually all FAMC were CD3-negative and cytokeratin-negative. Similar percentages of FAMC from EMPE and transudative effusions expressed the monocyte-lineage markers CD11b and CD14, suggesting that the proportion of monocyte-like mononuclear phagocytes in the pleural space is not increased during local tumor-associated inflammatory responses. The FAMC from EMPE (1) expressed HLA-DR antigens, (2) released interleukin 1 (IL-1) beta and tumor necrosis factor (TNF) alpha, and (3) stimulated allogeneic T-lymphocyte proliferation. The results of this study suggest that pleural mononuclear phagocytes may be involved in tumor-associated inflammatory reactions in the pleural compartment by stimulating the proliferation of other inflammatory cells and by releasing inflammatory cytokines.

A rapid semiautomatical enzyme linked immunoassay identifying intercellular adhesion molecule-1 (ICAM-1) on the alveolar macrophage surface

Intercellular adhesion molecule-1 (ICAM-1), a member of the immunoglobulin gene superfamily, is a cytokine-inducible adhesion molecule, which plays a central role in leukocyte migration into sites of acute or chronic inflammation. In this article we describe a sandwich immunoenzymometric method which allows rapid, semiquantitative (in "enzyme immunoassay units", EU) identification of ICAM-1 on the surface of alveolar macrophages. We evaluated this method in two groups of patients with pulmonary sarcoidosis (n = 12) or bacterial pneumonia (n = 11) and a group of healthy volunteers (n = 6), comparing the results with those obtained by immunocytochemical staining. ICAM-1 expression on the sarcoid alveolar macrophages surface was significantly elevated, as compared with control alveolar macrophages (0.76 EU +/- 0.27 vs. 0.44 EU +/- 0.12, p < 0.01). ICAM-1 expression on the surface of alveolar macrophages from patients with pneumonia was not elevated (0.48 EU +/- 0.35). Stimulation with tumour necrosis factor-alpha (TNF-alpha) or interferon-gamma (100 kU/l) led to a significant induction of ICAM-1 on the surface of control alveolar macrophages (0.76 EU +/- 0.18, p < 0.005 for TNF-alpha, 0.64 EU +/- 0.10, p < 0.005 for interferon-gamma), whereas alveolar macrophages from both patient groups did not respond to cytokines even at high dosages. ICAM-1 expression on the surface of alveolar macrophages from patients with sarcoidosis correlated with the spontaneous release of TNF-alpha by macrophages (R = 0.77, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Mycobacterium tuberculosis alters expression of adhesion molecules on monocytic cells

The host response to Mycobacterium tuberculosis is characterized by interactions between mononuclear cells, with recruitment and fusion of these cells culminating in granuloma formation. In addition, the host response to M. tuberculosis requires CD4+ T-cell reactivity, mediated by antigen-independent as well as antigen-dependent mechanisms. Thus, we hypothesized that cell adhesion molecules such as intercellular adhesion molecule 1 (ICAM-1; CD54) would participate in the response to infection with M. tuberculosis. Exposure of THP-1 cells derived from a monocyte/macrophage cell line to M. tuberculosis (1:1 bacterium/cell ratio) elicited a sustained increase (660% +/- 49% above resting level) in the expression of ICAM-1 that continued for at least 72 h. Neither the expression of vascular cell adhesion molecule 1 (VCAM-1; CD106) nor that of the integrins lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18) or CR3 (CD11b/CD18) was increased to a similar extent at corresponding time points. The increase in ICAM-1 protein expression was accompanied by an increase in steady-state mRNA (Northern [RNA] analysis). Neutralizing monoclonal antibodies directed against tumor necrosis factor alpha but not interleukin 1 alpha or interleukin 1 beta substantially abrogated the response to M. tuberculosis consistent with a paracrine or autocrine response. Continuous upregulation of the expression of ICAM-1 on mononuclear phagocytes induced by M. tuberculosis may mediate the recruitment of monocytes and enhance the antigen presentation of M. tuberculosis, thus permitting the generation and maintenance of the host response.

Expression of surface markers on alveolar macrophages from symptomatic patients with HIV infection as detected by flow cytometry

Alveolar macrophages (AMs) harvested from 32 HIV-infected patients with respiratory problems (opportunistic pulmonary infections, n = 12; other lung disease, n = 20) and 13 healthy controls were stained with a panel of 15 monoclonal antibodies directed against surface antigens implicated in cell function. Antigen expression was quantified by flow cytometry and expressed as relative linear median fluorescence intensity (RLMFI). On AMs of patients, as compared with controls, there was a significant enhancement of HLA DP (12.1 +/- 1.5 vs 6.5 +/- 0.9, p = 0.01, M +/- SEM, RLMFI units), CD11b (3.4 +/- 0.5 vs 1.7 +/- 0.4, p = 0.014), CD11c (8.9 +/- 1.0 vs 4.8 +/- 0.8, p = 0.0046), CD14 (2.1 +/- 0.3 vs 1.0 +/- 0.2, p = 0.0009), and CD33 (1.7 +/- 0.1 vs 1.0 +/- 0.2, p = 0.0093). No significant differences could be established for HLA-DR (36.9 +/- 5.8 vs 30.9 +/- 7.5, NS), HLA-DQ (3.4 +/- 0.3 vs 3.1 +/- 0.6, NS), CD54 (1.9 +/- 0.3 vs 1.2 +/- 0.1, NS), CD13 (2.5 +/- 0.6 vs 1.5 +/- 0.3, NS), CD36 (1.4 +/- 0.2 vs 0.9 +/- 0.3, NS), CD71 (10.3 +/- 1.9 vs 8.9 +/- 1.8, NS), CD25 (0.8 +/- 0.0 vs 0.9 +/- 0.1, NS), 27E10 (1.1 +/- 0.1 vs 0.8 +/- 0.3, NS), RM3/1 (1.9 +/- 0.4 vs 1.5 +/- 0.4, NS), and CD4 (1.5 +/- 0.3 vs 1.0 +/- 0.0, NS). The expression of CD14 and CD11b, but not of HLA class II antigens and CD71, was increased in the smaller cell population compared with the larger, thus suggesting monocyte recruitment. The increased expression of HLA-DP, CD11c, CD14, and CD33 on the patients' AMs was independent of smoking habits. The degree of immunodeficiency as indicated by the absolute peripheral CD4 count, the character of HIV-related pulmonary disease, and the prophylactic use of pentamidine or zidovudine did not significantly modify the antigen expression pattern. It is concluded that HIV infection may lead, most probably indirectly, to enhanced expression of surface antigens by local upregulation and/or recruitment of monocytes from the peripheral circulation. The functional significance of enhanced marker expression requires further clarification.

Enrichment and characterization of dendritic cells from human bronchoalveolar lavages

In the present study about 0.3% to 1.6% of human bronchoalveolar lavage (BAL) cells were identified as typical dendritic cells (DC), having an irregular outline, lobulated nucleus, and clear distinguishable acid phosphatase activity or EBM11 (anti-CD68) reactivity in a spot near the nucleus. After DC enrichment, using transient adherence to plastic, FcR-panning, and a density metrizamide gradient, a population containing 7-8% typical DC was obtained. This DC-enriched low density fraction, containing the highest percentages of DC, very strongly induced T cell proliferation in an allogeneic mixed leucocyte reaction (MLR), which was significantly higher than that induced by other partly (un)fractionated BAL cells. These data indicate that DC seem to be the major accessory cells in the BAL fluid, and therefore may be important in the regulation of T cell immune responses in the lung.

Adhesion molecules in lung diseases

The human body possesses highly specialized cellular defense mechanisms that, when activated pathologically, can induce a number of immunologic disorders. For a normal cellular immune response, the following conditions must be fulfilled: (1) accumulation of white blood cells, (2) their diapedesis through the vessel walls of the inflammatory area affected by an injurious agent, and (3) normal cellular effector functions in the tissue. This cascade of inflammatory processes has recently been shown to be regulated by a group of molecules that are termed adhesion molecules and consist of three subfamilies: selectins, the immunoglobulin supergene family, and integrins. The cellular functions influenced by adhesion molecules include, among others, cytotoxic T-cell responses, CD4-dependent activation of B lymphocytes by T lymphocytes, activation of granulocytes and macrophages, phagocytosis of opsonized particles by monocytes, macrophages, and granulocytes, antigen-presenting function of macrophages, their antibody-dependent cytotoxicity, initiation of a respiratory burst by white blood cells, and activation of fibroblasts. Studies performed in recent years have shown that pathogenetically relevant changes in the expression and function of adhesion molecules are involved in a variety of pulmonary diseases. These changes include the accumulation and activation of alveolar macrophages in smokers, experimentally induced bronchial hyperreactivity in bronchial asthma, accumulation of eosinophils in allergic rhinitis, bleomycin-induced pulmonary fibrosis, binding of viruses and bacteria to respiratory mucosa, and various mechanisms of acute damage to pulmonary parenchyma. Though their role in tumor development is still unclear, adhesion molecules are obviously involved in determining the route and organotropism of metastases. Further studies of the function of adhesion molecules in pulmonary diseases will contribute to our understanding of the pathomechanisms of these diseases and, through the development of specific antibodies, may provide attractive new therapeutic approaches to problems for which treatment is not yet available.

Soluble intercellular adhesion molecule-1 (ICAM-1) in sera and bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis and pulmonary sarcoidosis

ICAM-1 plays an important role in inflammatory diseases. To assess level of soluble ICAM-1 in the circulation and inflamed lesions, we measured levels of soluble ICAM-1 in the circulation and bronchoalveolar lavage fluid (BALF) of patients with idiopathic pulmonary fibrosis (IPF) and with pulmonary sarcoidosis (PS) and of healthy volunteers (HV), and we also analysed ICAM-1 expression of BALF cells in some patients and HV. IPF patients had significantly higher levels of circulating ICAM-1 than HV, while PS patients did not. By contrast, significantly increased levels of BALF soluble ICAM-1 were found in PS patients compared with those of HV, but not in IPF patients. There were no significant differences in the proportions of ICAM-1+ BALF lymphocytes in IPF patients, PS patients and HV, whereas significantly increased proportions of ICAM-1+ pulmonary alveolar macrophages were found in PS patients compared with those of HV, but not in IPF patients. There was a significant positive correlation of BALF soluble ICAM-1 levels to BALF lymphocyte proportions in PS patients. Although the source of BALF soluble ICAM-1 is unclear, BALF soluble ICAM-1 appears to reflect the grade of local activity of sarcoidosis. An interesting discrepancy between soluble ICAM-1 levels in the circulation and BALF was found in IPF patients, and this might be an important clue to an understanding of this disorder.

Recurrence of sarcoidosis in pulmonary allograft recipients

Lung transplantation is a potentially curative therapy for the end-stage pulmonary sequelae of sarcoidosis. We reviewed the course of five lung allograft recipients with underlying sarcoidosis (S) at the University of Pittsburgh Medical Center and compared them with a control group (C) of 44 contemporaneous transplant recipients with other respiratory diseases. Sarcoid granulomata have developed in the allografts of 4 S, although these lesions have not yet been demonstrated to result in clinically significant abnormalities. In comparison with C, sarcoidosis patients had significantly greater mean grades of acute rejection during the first 3 months after transplantation (2.1 +/- 0.3 versus 1.6 +/- 0.1, S and C, respectively, p < 0.042) and larger proportions of lung biopsies showing more than mild acute rejection (40 versus 18%, p < 0.012) and lymphocytic bronchitis (30 versus 13%, p = 0.02), as well as a greater percentage of polymorphonuclear leukocytes in BAL returns (34.9 +/- 5.4 versus 19.0 +/- 1.6, p < 0.01). The two groups did not differ, however, in frequency of obliterative bronchiolitis, survival, or pulmonary function. We conclude that lung transplant recipients with underlying sarcoidosis are very likely to develop recurrent disease in the allograft and have more severe acute rejection responses, especially in the first weeks after transplantation. Pulmonary transplantation appears to be an efficacious therapy for end-stage sarcoidosis, but the long-term sequelae of the increased acute rejection and recurrent sarcoidosis in the allograft remain to be determined.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Phenotypic markers of alveolar macrophage maturation in pulmonary sarcoidosis

The expression of maturation-associated antigens on alveolar macrophages (AMs) was studied in bronchoalveolar fluid of 30 patients with sarcoidosis and 11 control subjects. The percent of AMs expressing CD14 or CD11b (common for blood monocytes) was significantly increased in patients with active sarcoidosis compared to those with inactive disease, and control subjects. On the other hand, the mean expression of antigens characteristic for mature macrophages showed no significant difference (25F9), or was even increased in patients with sarcoidosis (CD71, KiM8). Since CD14 and CD11b molecules were also frequently expressed on large phagocytes morphologically similar to mature macrophages, and recent studies showed modulation of these glycoproteins by the activation of myeloid cells, our data indicate that the majority of AMs recovered by bronchoalveolar lavage in sarcoidosis are mature, activated cells.

Increased number of alveolar macrophages expressing surface molecules of the CD11/CD18 family in sarcoidosis and idiopathic pulmonary fibrosis is related to the production of superoxide anions by these cells

This study was designed to investigate the expression and functional properties of leukocyte adhesion molecules (LeuCAM; CD11/CD18 family) on human alveolar macrophages (AM) from patients with sarcoidosis and idiopathic pulmonary fibrosis. Cells were obtained by bronchoalveolar lavage (BAL) from 17 patients with sarcoidosis (SA), 15 with idiopathic pulmonary fibrosis (IPF), and 14 nonsmokers (NS). Expression of LeuCAM on freshly isolated cells was studied using the peroxidase-antiperoxidase method with monoclonal antibodies (MoAb) detecting CD11a, CD11b, CD11c, and CD18. The functional properties of the adhesion molecules were studied by measuring superoxide anion production (O2-) of SA and IPF AM after blocking the CD18 molecule by an MoAb. Compared with nonsmokers, the samples from SA and IPF patients contained an increased number of AM expressing CD11a, CD11b, CD11c, and CD18 (all p < 0.008), which was correlated to the number of AM/ml BAL (p < 0.008). Spontaneous O2- secretion of AM was higher in SA (6.4 +/- 1.2 nMO2-/10(6) AM/120 min) and IPF (12.0 +/- 1.1 nMO2-/10(6) AM/120 min) compared with NS (2.5 +/- 0.2 nMO2-/10(6) AM/120 min) (both p < 0.008). Incubation of the AM with the MoAb anti-CD18 reduced the spontaneous O2- release from SA AM by 52 +/- 8% and from IPF AM by 49 +/- 3% but did not influence O2- release from NS AM (92 +/- 4%). Our data indicate that the increased expression of LeuCAM on AM in subjects with SA and IPF seems to be involved in the increased O2- production of these cells in both diseases.

Increased secretion of tumor necrosis factor-alpha, interleukin-1-beta, and interleukin-6 by alveolar macrophages from patients with sarcoidosis

BACKGROUND

Alveolar macrophages from patients with sarcoidosis were analyzed for their ability to secrete tumor necrosis factor-alpha (TNF-alpha), interleukin-1-beta (IL-1-beta), and interleukin-6 (IL-6).

RESULTS

Constitutive release of all three monokines in these patients was concomitantly increased in the active state of disease in comparison with inactive sarcoidosis or healthy control subjects. Alveolar macrophages from patients with inactive sarcoidosis compared with cells from healthy subjects showed increased spontaneous secretion of TNF-alpha and IL-6 only, whereas the constitutive release of IL-1-beta was similar as in healthy volunteers. In vitro stimulation of alveolar macrophages from healthy control subjects with lipopolysaccharide or pokeweed mitogen led to a time- and dose-dependent enhanced secretion of TNF-alpha, IL-1-beta, and IL-6. In a similar manner, with corresponding cells from patients with sarcoidosis the secretion of all three cytokines could be further increased by stimulation with lipopolysaccharide or pokeweed mitogen.

CONCLUSIONS

The data presented indicate that an increased release of TNF-alpha, IL-1-beta, and IL-6 correlates to disease activity and may play a critical part in the pathogenesis of sarcoidosis.

Differentiation-related expression of ICAM-1 by rat alveolar epithelial cells

Local regulation of immune and inflammatory responses within the alveolar space is a critical aspect of normal pulmonary host defense. The type I and type II epithelial cells that line the alveolar space are in intimate contact with lymphocytes and macrophages within the alveolar space and are ideally situated to provide regulatory signals to these effector cells. The present studies were undertaken to investigate the expression by rat alveolar epithelial cells in vitro and in vivo of intercellular adhesion molecule-1 (ICAM-1), an adhesion molecule that is involved in migration and activation of T cells and macrophages. An antibody specifically blocking rat ICAM-1 (mAb 1A29) inhibited the adherence of activated T lymphoblasts to monolayers of type II alveolar epithelial cells. The expression of ICAM-1 protein by alveolar epithelial cells in vitro was confirmed both by immunofluorescence microscopy and by Western blot analysis. However, in each instance, ICAM-1 was not detected in type II cells the day of isolation, but appeared at low levels after 1 day and in abundance throughout the monolayer after 2 days, with sustained expression thereafter. This suggested that ICAM-1 expression might be a type I cell feature, which was induced as isolated type II cells underwent transformation towards the type I cell-like phenotype in vitro. Using immunofluorescence microscopy on frozen sections of normal lung, ICAM-1 was found in a linear distribution along the alveolar space, consistent with expression on type I cells.(ABSTRACT TRUNCATED AT 250 WORDS)