Spectrum of Alveolitis in Quartz-Exposed Human Subjects

Spectrum of Alveolitis in Quartz-Exposed Human Subjects* Raymond 0. Begin, M.D., F.C.C.P.;t Andre M. Cantin, M.D., F.C.C.P.;:j: Robert D. Boileau, M.D., F.C.C.P.;:j: and Guy Y. Bisson, M.D.:j:

To characterize silica-induced alveolitis in human subjects, we studied 22 workers in the granite stone cutting industry of Quebec and compared results with those of 22 manual workers without quartz exposure (group I~ All were nonsmokers and were of comparable age. On the basis of chest roentgenogram, seven were without disease (group 2~ nine

Jnhalation ofsilica dust can lead to chronic lung injury

and progress to overt clinical silicosis. Current concepts on the pathogenesis of silicosis have evolved from the older theory that silica dust in the lung was rapidly causing injury and disruption of the macrophage resulting in the release of toxic substances from the dying macrophages. Indeed, recent studies in human subjects1-:i and in the animal modelsu have documented that silica-laden macrophages maintain normal viability and phagocytic ability but may be activated to produce proinflammatory mediators which would initiate the disease process. Some of these mediators have been suggested on the basis of in vitro studies (interleukin, chemotaxis, macrophagederived growth factor) and are extensively discussed in the review of Davis. 7 As the lung tissue clearance of silica dust is very slow, 8 the silica-laden macrophages would remain chronically activated to produce a sustained release of these pro-inflammatory mediatorss.s which would perpetuate the inflammatory process leading to silicosis. To characterize this chronic inflammatory process in silica exposed humans, Schuyler et al1 have performed bronchoalveolar lavage (BAL) on eight patients with complicated silicosis. They have documented normal viability and phagocytic ability of the macrophages and observed increased numbers of type II pneumocytes in the lavages. In a study of nine healthy Vermont granite workers without clinical silicosis, the phagocytic function and viability of the dust-laden macrophage were confirmed, 1.3 and the investigators also reported a subclinical immune inflammatory response characterized by excessive accumulation of

had silicosis without coalescence/conglomeration (group 3~ and six bad silicosis with coalescence/conglomeration (group 4~ The alveolitis in subsets of silica-exposed workers with distinct clinical stages of disease was found to have distinct biologic characteristics.

lymphocytes and immunoglobulins. 3 In this article, we report detailed clinical, functional, and BAL analyses in a group of 22 long-term silica-exposed workers with a broad spectrum of disease that ranges from exposed workers without clinical disease to simple silicosis and complicated silicosis. Furthermore, to investigate the mechanisms of fibrosis in silicosis, we have measured fibronectin, procollagen 3 peptides, and fibroblast growth factors in BAL and analyzed these observations in relation to the clinical stage of the disease. MATERIALS AND METHODS Patients

The average age ofthe 22 workers in the study was 54±4 (SE) years (range 35 to 71), and they had been exposed to silica dust in the granite cutting industry of the Eastern lbwnships of Quebec for an average of 31 years (range 18 to 40); they had no prior history of pulmonary disease. All were nonsmokers for more than three years at the time of study. All were referred to us for pulmonary evaluation by their family physician either on the basis of abnormal findings on chest x-ray film or on the request of the patients who were aware of the risk of their trade. Four of the six workers with complicated silicosis were retired for at least one year. All others were current workers in the industry, with exposure up to 48 hours prior to evaluation. The granite industry of the Eastern Townships of Quebec is primarily a shed-work type of industry where blocks of granite are cut, carved, and polished in indoor sheds and the finished products used in large building construction. The granite material comes from all over North American quarries, on the basis of the buyers needs and requirements. On the average, tested samples obtained from the industry have demonstrated that they contain 30 to 60 percent silicon dioxide, and recent surveys of the sheds have documented that quartz levels in the room air of the sheds were at 1 to 4 mr/m3 (threshold limit value for quartz is 0.2 mrJm3).

Control Subjects *From the Unite de Recherche Pulmonaire, CHUS, Sherbrooke, Quebec, Canada. this study was supported by IRSST Quebec. tProfessor of Medicine. :!:Assistant Professor of Medicine. Reprint requests: Dr. Begin, Centre Hospitalier Universitaire, Slierbrooke, Quebec, Canida ]lH 5N4

1\venty-two manual workers without silica exposure were tested within the period. They were matched fur age, height and sex to the silica-exposed workers; all were nonsmokers for more than three years. The mean age of control subjects was 44 ± 6 years. None of them was exposed to environmental dust at risk of pneumoconiosis. They constituted group 1 in this report. CHEST I 92 I 8 I DECEMBER, 1987

1081

Dlagnoais of Silicosis As recommended previously,• the diagnosis of silicosis was based on a history of prolonged exposure to silica containing dust and a chest roentgenogram demonstrating changes consistent with silicosis in category 1 or above according to the ILO classification. JO

Subaets

of Sillca-Ezpoaed Workers

On the basis of chest x-ray classification, the 22 silica \IVOrkers were divided into three groups for comparison to control subjects (group 1). Group 2 was composed of seven \IVOrkers who did not meet the diagnostic criteria for silicosis. Group 3 was composed of nine \IVOrkers with simple silicosis without coalescence or large opacity on chest x-ray film. Group 4 was composed of six \IVOrkers with silicosis and coalescence or conglomerates. There was no significant dift'el'ence in past cigarette smoking index between groups (averaging 20::t5 pack-year).

CUnical Evaluation All patients had a history and complete physical examination with emphasis on the detection of abnormalities suggestive of silicosis. More specifically, a questionnaire directed at eliciting respiratory symptoms and factors associated with chronic obstructive pulmonary disease, lifetime smoking habits, and occupational history was administered. Silica exposure time for each \IVOrker was computed as the number of years of employment in a silica dust \\'Ork environment. More specific exposure indices were impossible to obtain with accuracy in each \IVOrker, as dust levels of exposure in these sheds were not measured until recently, and as individual exposures vary from task to task, from shed to shed, and also depend on individual \\'Ork habits. Intermediate PPD skin tests were not done routinely as all had BCG vaccination in childhood. Chest roentgenogram and spiromebic data were also available from previous evaluations in our institution and used to determine the rate of changes in lung disease profusion and changes in vital capacity over an average five-year

period.

Chut Roentgenograma Standard high kilovoltage posteroanterior, lateral, and oblique films were obtained at maximal inspiration. The lung parenchyma was graded fur profusion of small opacities by three observers according to the International Labor Organimtion (ILO) classification and averaged fur each film. When in the presence of major dift'erences between readers, each film was reviewed by the three readers together to determine the final grade. The profusion of irregular opacities was scored on a linear scale of 0 to 10; grade Oland 0/0=0; M=l; 1/0=2; 111=3; 112=4; M=S; ~2=6; ~=7; 312=8; 313=9; 314=10. The category of profusion is based on viewers assessment of the concentration of opacities by comparison with the standard roentgenograms provided by the ILO. This classification recognizes the existence of a continuity of change from no small opacities (0/- or 0/0) to the most advanced category (31 + ). The profusion of opacities was recorded to yield the usual global score of profusion. Coalescence of opacities is classifled as AX and large opacities are scored A, B or C depending on the si7.e. 111 The symbols AX, A, B, and C were converted numerically 1 to 4 and added to the score of opacity profusion.

Pulmonary

FUnclion The lung volumes, pressure-volume curves, Bow-volume curves and diffusion capacities (Dco) were measured by the standard methods in our laboratory. F\Jnctional residual capacity (FRC) was determined by the helium rebreathing method, and after initial equilibration, at least three vital capacity scores were obtained to measure all lung volumes. The static expiratory lung compliance was obtained by monitoring transpulmonary pressure using a 7-ml balloon catheter and an airway catheter sampling pressure at the

1082

mouth connected to a dift'erential transducer (Hewlett-Packard) and by monitoring gas flow at the airway opening with a pneumotachograph (Fleisch No 2) attached to a Bow meter integrator recorder system. For each subject, after a standard volume history was obtained, the maximal esophageal pressure (P_mu) at total lung capacitywas obtained in biplicate with the airway opened during the third second of breathholding. Thereafter, inspiratory capacities were repeated to obtain some 20 points on the expiratory phase of the maneuver, again during the third second of breathholding. A best fit curve was drawn from all points and used for each subject. The predicted values in this study were those of Bates and co\IVOrkersu fur lung volumes and Dco and ofB6gin and assoofatesD pressure-volume curves.

m

Ga Scan

11

Fifty microcuries per kilogram body weight of 11Ga citrate was injected intravenously into each patient. Forty-eight hours later, anterior and posterior scans from neck to pelvis were recorded with a camera (Dyna 4c/15-61) coupled with a microprocessor (Cromenco system 3). Sof\ware fur acquisition and processing of the data was developed in our institution. Grading of the 11Ga pulmonary uptake was done as recently reported. 11 Briefty, the index of "Ga lung uptake was obtained from the posterior scan. It was based on a 0to16 relative scale. The average background activity per pixel was estimated from a region in the abdomen below the kidneys. The background radioactivity was given a score ofO and subtracted from all areas. The maximal average activity of the liver within a region measuring approximately 6 x 6 cm was used as the internal standard and given a value ofl6. The global lung activity was expressed as an index based on its value relative to the two reference points. Mathematically, the index can be expressed as: Global lung index= av counts/pixel in lunp- background av counts/pixel 16 x maximal liver av counts/pixel- background av counts/pixel The final data were visually represented on a 128x128 pixel frame, smoothed and color coded to a 16 color scale. This permitted a pixel by pixel quantification of the 17Ga uptake by the lungs, and it allowed scoring of dift'erent areas of interest and scoring ofhilar areas when of interest. 1b determine regional indices, the lung &elds were divided into six areas comparable with those of the International Labor Organimtion/University of Cincinnati (ILO/UC) classification of roentgenograms of pneumoconiosis, excluding the hilar areas. Within each area, the 17Ga lung uptake was averaged to yield a regional index. With this approach to quantitate "Ga lung uptake, the only subjectivity left was in the assignment ofregion ofinterest to be used in the data processing, but we have previously documented that the results do not vary significantly between readers (w"" 0. 91, p<0.01)."

Bnmchoaloeolar Laoage and Fluid Analyaii Most ofthe techniques in BAL procedures and analyses have been previously described. J5.l7 Briefty, lung lavage was perfurmed by slow infusion of three 50-ml 37"C aliquots of phosphate-buffered saline solution through a 50-ml Luel'-lock syringe attached to the \\'Ork channel of the bronchoscope and by gentle syringe aspiration of the efBuent. Lavage was carried out in a subsegment area where disease was most prominent on chest roentgenogram or fur the \IVOrkers with normal roentgenogram, lavage was carried out in the lower lobes. A 20 ml aliquot of the BAL efBuent was sent microbiologic cultures. and positive cultures excluded the subject from the study. The BAL efBuent was passed through four layers of cheesecloth to remove mucus, and the cells were pelleti7.ed by centrifugation. Cells were counted in a hemocytometer, and cell viability was determined by the trypan blue exclusion technique. Cytocentrifuge smears served to identify the cellular populations recovered with the \\TightGiemsa and naphthyl acetate esterase stains with no significant dift'erence in the results between the two techniques. In the

m

supernatant, albumin, lgA, lgG, lgM immunoglobulins, and fibronectin were measured by the immunochemical methods of Killingsworth and Savory, 11 using the Behring laser nephelometer Instrument. The BAL procollagen 3 was measured as type 3 procollagen N-terminal peptides by radioimmunoassay as reported by Low et al11 based on the method originally described by Rohde et al.., All results were expressed per milliliter of BAL fluid. All values of humoral components of BAL were also analyzed in terms of ratio to the albumin content of BAL supernatant. Fibrobl.ast ProUferation A11ay

REsui:rs

Clinical Data The profusion of disease on chest roentgenogram

was 0.50 ± 0.27 in control subjects (group 1), 1. 06 ± 0.19 in silica-exposed workers without silicosis (group 2), 3.54±0.26 in workers with simple silicosis (group 3), and 5.27±0.36 in workers with complicated silicosis

Alveolar lining fluid was analyzed fur the presence of molecules capable of enhancing fibroblast proliferation. Bronchoalwolar lavage fluid was centrifuged, 500 x g, five minutes and the supernatant was dialyzed extensively against distilled water. Albumin concentration was determined by immunochemical method. 11 The lavage fluid was then lyophilized and reconstituted in sufficient Dulbecco's modified Eagle medium (DMEM) containing 100 U/ml penicillin and 100 f!.g/ml streptomycin to yield an albumin concentration of50 f!.g.'ml. The reconstituted lavage fluid was filtered through a 0.22 fi.M filter (Millex) befure incubation with the human lung fibroblasts. Diploid human fetal lung fibroblasts (HFL-1; ATCC CCL-153)'1were grown to confluence in DMEM, 10 percent calf serum treated with 0.5 mg/ml trypsin and 0.2 mg/ml EDTA, and seeded in 24 mm culture wells at a density of 5x10' cells/well in DMEM 0.4 percent calf serum, 10 percent CO., 37"C, fur fuur days. The cells were then washed three times with phosphate buffered saline solution and incubated with lavage fluid containing 50 f!.Wml albumin at 37"C, 10 percent C01 fur three days. At the end of the incubation, the cells were treated with trypsin/EDTA fur 15 minutes and counted in an electronic particle counter. Each experiment included a negative control consisting of fibroblasts incubated with DMEM alone and a positive control consisting of DMEM + 10 percent calf serum. The results were expressed as the percentage of Increase In fibroblast number over control values. Staff8tlcal Analy.ria

All results are expressed as the mean± SD. The data were tested by the Students t-test or Mann-Whitney U test !Or differences between groups, by Wilcoxon matched-pairs signed-rank test fur differences between roentgenographic methods and by Spearmans correlation procedure when appropriate. a.a C:a-67

6 RADIOCRAPHIC SCORE OF DISEAS~

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The results of cellularity of BAL are presented in Figure 2 as total and diKerential cell counts as well as per ml of BAL effluent. In this study, effluent was similar in groups 1 to 4, averaging 62 ± 5 percent of effiuent. In group 1 (control subjects), BAL cellularity

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(group 4). In Figure l, we present for the four groups, the 117Ga lung uptake score, difference between current and previous roentgenogram score, and selected lung function data. The 11Ga lung uptake was 1.9±0.4 in group 1, 4.45±0.5 in group 2, 4.55±0.5 in group 3, and 7.5 ± 0. 7 in group 4 (p<0.05 for groups 2, 3, or 4 vs group l; p<0.05 for group 4 vs groups 2 or 3). The lung pressure-wlume curve was significantly more rigid in group 4 with compliance value of0.24 ± 0.03 UcmH10 as compared to 0.30±0.02 in group l, 0.33±0.04 in group 2, and 0.28 ± 0. 02 in group 3 (p<0.05 for group 4 vs groups 1 or 2). Reductions in vital capacity, expiratory flow rates and Dco (data not shown) paralleled the changes in lung compliance. In Figure 1, whereas it is clear that the rate of progression of roentgenographic score of disease and loss of lung function were the highest in men with complicated disease (group 4), significant progression of disease and loss of function were also seen in workers with simple silicosis (group 3).

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CHEST I 92 I 8 I DECEMBER, 1887

1083

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was comparable to that of our previous reports. In the silica-exposed workers (groups 2 to 4), we observed twice as many total cells, with prominent increases in macrophages and some increases in lymphocytes and neutrophils in all groups of exposed workers. Cellularity of BAL did not differentiate the three groups of silica-exposed workers with different severity of disease. The biochemical analyses of BAL supernatant are presented in Figure 3. Significant increases in the immunoglobulin IgM were seen in groups 2 to 4, with

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FIGURE 2. Lung lavage cellularity in the same fuur groups as in Figure 1. The data are expressed in terms of total and differential cellularity as well as per ml of lavage efBuent. Asterisk identifies significant differences with group 1.

the highest value in group 4, without parallel increase in serum IgM. The results of fibronectin and procollagen 3 were significantly increased only in group 4, the workers with complicated disease. Fibroblast proliferation capacity of lung lavage fluid was round at 33 ± 8 percent in group 1, 1±20 percent in group 2,

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60 ± 22 percent in group 3 and 67 ± 26 percent in group 4 (p
Fig 4).

DISCUSSION

The present study of 22 workers with relatively high intensity silica exposures and with clinical distinct manifestations of disease documents that (1) 117Ga lung uptake is enhanced in all exposed workers of this study and the uptake is further increased at sites of coalescence/conglomeration; (2) the cellularity of lung lavage is increased in all subsets of our silica-exposed workers as are the elevated levels of the immunoglobulin IgM; (3) BAL biochemical markers of fibrogenic activity are increased only in workers with coalescence/conglomeration; and (4) whereas silica-exposed workers without silicosis have BAL fluid that inhibits the proliferation of lung fibroblast, the workers with simple or complicated silicosis (groups 3 and 4) have BAL fluids that enhance the proliferation offibroblasts. This study further supports the concept that in silica-exposed workers, airflow limitation progresses with the severity of the disease. These biologic data of lung lavage in our workers with relatively high intensity exposures therefure document clearly that the clinical spectrum of silica-induced lung injury in human subjects is clearly reflected on the biologic characterization of lower respiratory tract fluid at various stages of disease. Because personal dust exposure history of each worker was not available, we could not relate BAL findings with cumulative exposures of the workers. The 117Ga lung uptake in silicosis has been previously reported by independent investigatorsl3.M as recently reviewed by us. 111 In this report, we document that the increased uptake is associated with increased cellularity even in the absence of roentgenographically detectable disease (group 2) and that the uptake is clearly more elevated at sites of coalescence/conglomeration, manifestations which are also associated with increased markers of fibrogenic activity. Thus, 117Ga scan could provide additional infurmation in establishing an early diagnosis of simple silicosis when borderline roentgenogram is in the grade Oil or 1/0. Also, when simple silicosis is well established on chest roentgenogram, we have documented that by CT scan, conglomeration could be visualized in 33 percent of cases.• In that situation, fucal accumulation of 117Ga could also favor staging the disease as complicated, establishing clinical indication fur further investigations of the disease process, to rule out other diseases such as tuberculosis or lung cancei; which also accumulate 117Ga. The characterization of the lower respiratory tract cellularity in silica-exposed workers has been reported in workers without roentgenographically detectable diseasel.3 and in workers with complicated silicosis. 1

The Vermont reports of workers exposed to less than the threshold limit value (TLV) without disease have documented significant increases in lymphocytes and lgM immunoglobulin in BAL fluids and suggested that this subclinical alveolitis could be important in the pathogenesis of silicosis. The Louisiana study on workers with complicated silicosis has emphasized the increased number of type II pneumocytes in lavage, 1 the latter finding possibly related to short, high intensity exposures of sandblasters. In this report, we present data on workers exposed to more than the TLV, without disease and our findings of elevated lymphocyte and lgM concentrations are in agreement with the Vermont study but differ in that we also fuund increased numbers of macrophages and neutrophils which may reflect higher intensity exposures in our workers. In workers with simple silicosis, our findings are similar to those of exposed workers without disease except fur increased levels of lung fibroblast growth signals. In workers with complicated silicosis, we also fuund increased levels oflung fibroblast growth signals which were also associated with lung lavage increases in glycosaminoglycans, fibronectin, and procollagen 3, biologic markers of fibrogenic activity that have been reported in other fibrosing lung diseases. • 17.17.ao The increased BAL IgM in our workers confirms the previous observation of Calhoun et al3 in healthy Vermont granite workers. As in the lattei; this BAL finding was not associated with increased serum levels of lgM in our workers. This observation cannot be completely explained by increased membrane peI'meability because albumin with a lower molecular weight would be expected to rise the most. Thus, it is likely related at least in part to enhanced synthesis by the lung lymphocytes, likely modulated by the alveolar macrophage. 31 Of interest, similar increase in BAL lgM has been documented in organic dust-exposed workers with hypersensitivity pneumonitis. 31.:13 In silicosis, the early histologic lesion consists mainly of concentric layers of fibroblasts and macrophages in the presence of silica dust. 34 As the disease becomes more extensive, the cellular silicotic nodule is replaced largely by connective tissue fibers comprised mainly ofcollagen. These nodules appear to conglomerate in the advanced stages of silicosis, yielding a histologic pattern of massive fibrosis. The close association of silica-laden macrophages with lung fibroblasts supports the hypothesis that alveolar macrophages obtained from silica-exposed lungs release large amounts of molecules capable of modulating fibroblast growth. :is.31 In patients with fibrosing lung disease, alveolar macrophages release large amounts of fibronectin and alveolar macrophage-derived growth factor (AMDGF). Fibronectin is a 440 kd glycoprotein that is chemotactic fur fibroblasts, mediates fibroblast attachment to matrix proteins, and provides a competence CHEST I 92 I 8 I DECEMBER, 1987

1085

signal fur fibroblast growth, 30•38 whereas AMDGF is an 18 kd protein which provides a progressiori type fibroblast growth signal. 37 In the present study, the lung extracellular milieu of exposed workers without silicosis inhibits the growth of lung fibroblasts, whereas that of workers with simple or complicated silicosis contained sufficient growth signals to enhance fibroblast proliferation in the absence of exogenously added growth factors. Interestingly, although patients with simple silicosis did not have increased amounts of the fibroblast products, fibronectin and procollagen 3, the capacity of the lavage fluid to induce fibroblast proliferation was similar to that of patients with complicated silicosis who had increased lavage fluid connective tissue components. These data are consistent with the concept that an increase in fibroblast growth modulating molecules in the silica-exposed lung may precede and direct the accumulation of fibroblasts and fibroblast products in advanced silicosis. These data are very consistent with the report of Lugano et al38 on the regulation of lung fibroblast proliferation by alveolar macrophages in experimental silicosis. Airflow limitation in mineral dust workers is a subject ofconsiderable debate. In silica-exposed workers, others have suggested that at least those with detectable disease have reduction in expiratory flow rates, 38•38 and our data on a relatively small sample of workers (Fig 1) are in agreement with these observations. In conclusion, this study documents that 87Ga lung scan and BAL analyses detected a subclinical alveolitis in our workers with relatively high intensity silica exposure and that alveolitis produces factors that inhibit lung fibroblast growth. In simple silicosis, the alveolitis produces factors that enhance lung fibroblast growth without detectable changes in BAL fluid of other markers of fibrosis. In complicated silicosis, the alveolitis produced all of the markers associated with a high intensity fibrotic process. This report thus documents several differences in the biological characteristics of alveolitis in subsets of silica-exposed workers with distinct clinical stages of the disease.

6 7 8 9 10 11 12 13

14 15 16 17

18 19 20

21

REFERENCES

1 Schuyler MR, Gaumer HR, Stankus RP, Kaimal J, Hoffman E, Salvaggio JE. Bronchoalveolar lavage in silicosis. Lung 1980; 157:95-102 2 Christman Jw. Emerson RJ, Graham WGB, Davis GS. Mineral dust and cell recovery from the bronchoalveolar lavage ofhealthy Vermont granite workers. Am Rev Respir Dis 1985; 132:393-99 3 Calhoun WJ, Christman Jw. Ershler WB, Graham WGB, Davis GS. Raised immunoglobulin concentrations in bronchoalveolar lavage fluid of healthy granite workers. Thorax 1986; 41:266-73 4 Brody AR, Roe MW, Evans JN, Davis GS. Deposition and translocation of inhaled silica in rats: quantification of particle distribution, macrophage participation, and function. Lab Invest 1982; 47:533-41 5 Davis GS, Hemenway DR, Evans JN, Lapenas DJ, Brody AR.

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22 23 24 25 26 27

Alve0lar macrophage stimulation and population changes in silica-exposed rats. Chest 1981; 80:8-10 B6gin k, Mass6 S, Rola-Pleszczynski M, Martel M, Desmarais~ Geof&oy M, et al. Aluminum lactate treatment alters the lung biological activity of quartz. Exp Lung Res 1986; 10:385-99 Davis GS. Pathogenesis ofsilicosis: current concepts and hypotheses. Lung 1986; 164:139-54 Mgin R, Mass6 S, Sllbastien P, Martel M, Bossli J, Dubois F, et al. Sustained efficacy of aluminum to reduce quartz toxicity in the lung. Exp Lung Res 1987; 13:205-22 'lllsk Force on Occupational Respiratory Disease. Health and Wel&te, Ottawa, Canada, 1979:35-48 ILO/UC International Classification of radiographs of pneumoconiosis 1980 No. 22 revised. Occupational Safety and Health Series. Geneva: International Labour 08ice, 1980 Bates DV, Macklem PI: Christie Rv. The normal lung: physiology and methods of study. In: Respiratory function in disease. Philadelphia: WB Saunders, 1971: 11-9.;, 276-80 Mgin R, Renzetti AD, Bigler A, Watanabe S. Flow and age depehdence of airway closure and dynamic compliance. J Appl Physiol 1975; 8:199-207 Bisson G, Drapeau G, Lamoureux G, Cantin A, Rola-Pleszczynski M, Mgin R. ComputeP.based quantitative analysis of gallium-67 uptake in normal and diseased lungs. Chest 1983; 84: 513-17 Bisson G, Lamoureux G, B6gin R. Quantitative gallium 67 lung scan to assess the inflammatory activity in the pneumoconioses. Sem Nucl Med 1987; 17:72-80 B6gin R, Cantin A, Drapeau G, Lamoureux G, Boctor M, Massli S, et al. Pulmonary uptake of gallium-67 in asbestos exposed human and sheep. Am Rev Respir Dis 1983; 127:623-30 B6gin R, Cantin A, Berthiaume Y, Boileau R, Bisson G, Lamoureux G, et al. Clinical features to stage the alveolitis in asbestos workers. Am J Indust Med 1985; 8:521-36 B6gin R, Martel M, Desmarais Y, Drapeau G, Boileau R, RolaPleszczynski M, et al. Fibronectin and procollagen 3 levels in bronchoalveolar lavage of asbestos exposed human subjects and sheep. Chest 1986; 89:237-43 Killingsworth LM, Savory J. Manual nepheiometric methods fur immunochemical determination of immunoglobulins lgG, lgA and IgM in human serum. Clin Chem 1972; 18:335-39 Low RB, Cutroneo KR, Davis GS, Giancola MS. Lavage type m procollagen N-terminal peptides in human pulmonary fibrosis and sarcoidosis. Lab Invest 1983; 48:755-59 Rohde H, Vargas L, Hahn E, Kalbfleisch ii, Bruguera M, Thnpl R. Radioimmunoassay fur type m procollagen peptide and its application to human liver disease. Eur J Clin Invest 1979; 9: 451-59 Bradley KH, Kawanami 0, Ferrans VJ, Crystal RG. The fibroblast of human lung alveolar structures: a dift'erentiated celi with a major role in lung structure and function. In: Harris CC, 'Ihnnp BR, Stone GD, eds. Methods in cell biology, vol 21. New York: Academic Press, 1980:37-64 Snedecor GW, Cochran WC. Statistical methods. Ames, Iowa: Iowa State University Press, 1967 Siegel S. Non-parametric statistics. New-York: McGraw-Hill book, 1956:195-240 Siemsen JK, Sargent EN, Grebe SF, Winsor DW, Wentz D, Jacobson G. Pulmonary concentration of Ga-67 in pneumoconiosis. AJR 1974; 120:815-20 Mgin R, Bisson G, Boileau R, Massli S. Assessment of disease activity by Ga-67 lung scan and lung lavage in the pneumoconioses. Sem Respir Med 1986; 7:271-80 Mgin R, Bergeron D, Samson L, Boctor M, Cantin A. CT Assessment ofsilicosis in exposed workers. AJR 1987; 148:509-14 Crystal RG, Gadek JE, Ferrans VJ, Fulmer JD, Line BR, Hunninghake CW. Interstitial lung disease: current concepts ofpath-

ogenesis, staging and therapy. Am J Med 1981; 70:542-68 28 Rom WN, Bitterman P, Bennard S, Crystal RG. Alveolar macrophage mediated flbro~last proliferation in the pneumoconioses. Am Rev Respir Dis 1984; 129:160 29 Rom WN, Robinson B, McLemore TL, Rose CS, Crystal RG. Lung mononuclear cells &om individuals with chronic inorganic dust exposure spontaneously release immune interferon. Am Rev Respir Dis 1985; 131:189 30 Bennard SI, Hnnqinghake GW, Bitterman PB, Crystal RG. Production of &bronectin by the human alveolar macrophage: mechanism for the recruitment of fibroblasts to sites of tissue injury in interstitial lung diseases. Proc Natl Acad Sci 1981; 78: 7147-57 31 Calhoun WJ, Davis GS. Alveolar macrophages modulate the production of immunoglobulin by peripheral blood lymphocytes. Am Rev Respir Dis 1985; 131:46 32 Reynolds HY, Fulmer JD, Kazmierowski JA, Roberts WC, Frank MM, Crystal RG. Analysis of cellular and protein content of bronchoalveolar lavage fluid &om patients with idiopathic pulmonary fibrosis and chronic hypersensitivity pneumonitis. J Clin Invest 1977; 59:165-75 33 Cantin A, B6gin R, Boileau R, Drapeau G, Rola-Pleszczynski M.

34 35

36 37 38 39

Features of bronchoalveolar lavage differentiating hype~cmsitivity pneumonitis and pulmonary sarcoidosis at time of initial presentation. Clin Invest Med 1984; 7:89-94 Mark EJ. Dusts and aspiration. In: Lung biopsy interpretation. Baltimore: Williams and Wilkins, 1984:78-82 Lugano EM, Dauber JH, Elias JA, Bashey Iµ, Jimenez SA, Daniele RP. The regulation of lung fibroblast proliferation by alveolar macrophages in experimental silicosis. Am Rev Respir Dis 1984; 129:767-71 Bitterman PB, Rennard SI, Adelberg S, Crystal RG. Role of fibronectin as a growth factor fur fibroblasts. J Cell Biol 1983; 97: 1925-32 Bitterman PB, Rennard SI, Hnnninghake GW, Crystal RG. Human alveolar macrophage growth factor fur fibroblasts. J Clin Invest 1982; 70:806-22 lrwjg LM, Rocks P. Lung function and respiratory symptoms in silicotic and nonsilicotic gold miners. Am Rev Respir Dis 1978; 117:429-35 Man&edaJ, SidwallG, MainiK, WestP, CherniackRM. Respiratory abnormalities in employees of the hard roclc mining industry. Am Rev Respir Dis 1982; 126:629-34

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