Unusual hard metal lung disease: bronchiolocentric interstitial pneumonia.

A 38-year-old woman experienced a persistent dry cough and progressively worsening dyspnoea for 2 years. Spirometry testing revealed a moderate-to-severe restrictive abnormality. High-resolution chest computed tomography showed diffuse reticulonodular opacities. A lung biopsy disclosed alveolar parenchymal inflammation and fibrosis with bronchiolocentric features, prompting consideration of interstitial pneumonia. Following a thorough investigation of her occupational history and an on-site inspection, it was discovered that the patient had been grinding drill bits designed for printed circuit boards for 8 years, exposing her to hard metals. Mineralogical analyses confirmed excessive tungsten in urine, serum and hair, leading to a diagnosis of hard metal lung disease due to tungsten carbide-cobalt exposure. After discontinuing exposure and commencing corticosteroid therapy, her symptoms, pulmonary function and imaging showed modest improvement. This case highlights the significance of assessing occupational history in patients with interstitial pneumonia and understanding industrial hazards for accurate diagnosis and care.

MiADMSA abrogates sodium tungstate-induced oxidative stress in rats.

Tungsten (W) and its compounds have emerged as a relatively new area of environmental health concern in the last decade. Tungsten is environmentally benign due to its increasing use in armour-piercing munitions and as a replacement for lead in other ammunition. It has also been identified in various hazardous waste sites and therefore been proposed for inclusion in the Environmental Protection Agency National Priorities List. The major objective of this study was to evaluate the therapeutic efficacy of orally administered monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA) against tungstate induced oxidative injury in blood, liver and kidneys of male Wistar rats. MiADMSA, a thiol chelator has gained wide recognition recently as a future chelating drug of choice specifically for arsenic and was chosen for this study as tungstate ions too have an affinity toward the -SH group thus, being less bioavailable in the body. We determined the effects of MiADMSA (50 mg/kg, p.o.) against sodium tungstate (500 ppm in drinking water, daily for 28 days) induced biochemical changes indicative of oxidative stress in blood, and other soft tissues of of male Wistar rats. Tungsten exposure led to an increased levels of Reactive Oxygen Species (ROS) in liver, kidney, spleen and blood accompanied also by an increase in TBARS levels. The GSH: GSSG ratio also showed a decrease on sodium tungstate intoxication. Treatment with MiADMSA restored most of the sodium tungstate-induced alterations in the biomarkers suggestive of oxidative stress. These preliminary results led us to conclude that sub-acute exposure to tungstate-induced oxidative stress could be effectively reduced by the administration of MiADMSA and thus might be a promising antidote for studying in detail its efficacy in reducing body tungstate burden and its excretion post tungstate exposure.

Tungsten accumulates in the intervertebral disc and vertebrae stimulating disc degeneration and upregulating markers of inflammation and pain.

Tungsten is incorporated in many industrial goods, military applications and medical devices due to its ability to impart flexibility, strength and conductance to materials. Emerging evidence has questioned the safety of tungsten exposure as studies have demonstrated it can promote tumour formation, induce pulmonary disease and alter immune function. Although tungsten is excreted from the body it can accumulate in certain organs such as the brain, colon, liver, kidneys, spleen and bones, where most of the bioaccumulation occurs. Whether prolonged tungsten exposure leads to accumulation in other tissues is unknown. The present study demonstrated that mice exposed to 15 ppm sodium tungstate for 4 weeks in their drinking water showed comparable accumulation in both the bony vertebrae and intervertebral discs (IVDs). Lumbar IVD height was significantly reduced in tungsten-exposed mice and accompanied by decreased proteoglycan content and increased fibrosis. In addition to catabolic enzymes, tungsten also increased the expression of the inflammatory cytokines IL-1ß and tumour necrosis factor (TNF)-α as well as the neurotrophic factors nerve growth factor (NGF) and brain-derived nerve factor (BDNF) in IVD cells. Tungsten significantly increased the presence of nociceptive neurons at the endplates of IVDs as observed by the expression of calcitonin gene-related peptide (CGRP) and anti-protein gene product 9.5 (PGP9.5) in endplate vessels. The present study provided evidence that tungsten may enhance disc degeneration and fibrosis as well as increase the expression of markers for pain. Therefore, tungsten toxicity may play a role in disc degeneration disease.

Hard Metal Lung Disease with Favorable Response to Corticosteroid Treatment: A Case Report and Literature Review.

Hard metal lung disease (HMLD) is a pneumoconiosis caused by occupational exposure to hard metals such as tungsten carbide and cobalt, but the treatment strategies for HMLD have not been well established. A 68-year-old Japanese man with occupational history as a grinder of hard metals for 18 years referred to our hospital because of dry cough and dyspnea. A chest computed tomography (CT) on admission revealed centrilobular micronodules, ground-glass opacities, and reticular opacities in the peripheral zone of both lungs. Mineralogic analyses of lung tissues detected components of hard metals, such as tungsten, titanium and iron, and the same metals were also detected in the sample of the dust of his workplace. Thus, the patient was diagnosed as having HMLD based on occupational exposure history and radiologic and mineralogic analyses of the lung. Corticosteroid therapy was initiated, which resulted in partial improvements in his symptoms, radiological and pulmonary functional findings. In a review of the 18 case reports of HMLD treated with corticosteroids, including our case, the majority of patients (77.8%) showed favorable responses to corticosteroid treatment. Furthermore, the presence of fibrotic changes, such as reticular opacity, in radiological examinations was associated with the resistance to corticosteroids. In conclusion, the majority of patients with HMLD are expected to favorable response to corticosteroid treatment, whereas chest CT findings such as fibrotic changes may be predictive of the resistance of corticosteroid treatment. Lastly, proper prevention of hard metal exposure is most important as the first step.

[Investigation of contact dermatitis caused by hard metal dust].

Objective: To investigate the incidence of contact dermatitis among workers in cemented carbide production enterprises. Methods: From October 1997 to October 2017, an occupational epidemiological survey was conducted on a large-scale cemented carbide production enterprise, and occupational health examinations were conducted for employees. 152 people were exposed to hard metal dust (hard metal raw material dust and alloy dust) . The employees in the work group were contact groups, and 142 employees in the non-dusting operation of the company were in the control group. A detailed retrospective survey of hard metal production workers with contact dermatitis history in the two groups was conducted to analyze the risk factors of contact dermatitis exposure to hard metal dust. Results: The incidence of allergic diseases in the exposed group was significantly higher than that in the control group. The difference was statistically significant (χ(2)=23.793, P<0.05) . The incidence of contact dermatitis in the exposed group was significantly higher than that in the control group. The difference was statistically significant (χ(2)=24.659, P<0.05) ; the changes of contact dermatitis in the contact group were mainly allergic contact dermatitis, and some showed irritative contact dermatitis; the operator had respiratory symptoms (including work-related nasal congestion, cough, wheezing) , difficulty breathing may be the influencing factors of contact dermatitis (RR=2.60, 95%CI: 1.10-6.20, P<0.05) . Conclusion: Hard metal alloy enterprises are exposed to hard metal dust. The incidence of contact dermatitis is high in workers, and the occurrence of contact dermatitis may be associated with those with respiratory symptoms.

Investigating Serious Adverse Drug Reactions in Patients Receiving Erythropoiesis-Stimulating Agents: A Root Cause Analysis Using the "ANTICIPATE" Framework.

BACKGROUND: Unexpected serious adverse drug reactions (sADRs) affecting patients with chronic kidney disease (CKD) who received erythropoiesis-stimulating agents were identified by study co-authors. These included pure red cell aplasia (PRCA) after administration of the Eprex formulation of epoetin or the epoetin biosimilar HX575 and fatal anaphylaxis associated with peginesatide, an erythropoietin receptor agonist. We developed and applied a structured framework to describe these sADRs, including root cause analyses and eradication efforts. METHODS: A 10-step framework termed "ANTICIPATE," focusing on signal identification, incidence, causality, and eradication guided our evaluations. RESULTS: Initial cases were identified by a hematologist (Eprex), clinical study monitors (HX575), and 4 nurses (peginesatide). The number of persons with individual ADRs was 13 PRCA cases for epoetin, 2 antibody-mediated PRCA cases for HX575, and 5 fatal anaphylaxis cases for peginesatide. Initial incidence estimates per 1000 treated persons were 0.27 for Eprex-associated PRCA, 11 for HX575-associated PRCA, and 0.38 for peginesatide fatalities. Likely causes were subcutaneous administration of epoetin formulated with polysorbate 80 (Eprex), tungsten leaching from pins included in product syringes (HX575), and inclusion of a phenol stabilizer (peginesatide). Eradication strategies included restricting Eprex administration to the intravenous route, excluding tungsten from HX575 syringes, and for peginesatide, proposed eradication was to return to single-dose vials without preservatives. CONCLUSION: Although the number of cases of each sADR was small, eradication was successful for 2 sADRs, and a proposed eradication was developed for a third sADR. The structured framework used to describe the above 3 sADRs in patients with CKD can also be used in other clinical settings.

Tungsten exposure causes a selective loss of histone demethylase protein.

In the course of our investigations into the toxicity of tungstate, we discovered that cellular exposure resulted in the loss of the histone demethylase protein. We specifically investigated the loss of two histone demethylase dioxygenases, JARID1A and JMJD1A. Both of these proteins were degraded in the presence of tungstate and this resulted in increased global levels of H3K4me3 and H3K9me2, the substrates of JARID1A and JMJD1A, respectively. Treatment with MG132 completely inhibited the loss of the demethylase proteins induced by tungstate treatment, suggesting that tungstate activated the proteasomal degradation of these proteins. The changes in global histone marks and loss of histone demethylase protein persisted for at least 48 h after removing sodium tungstate from the culture. The increase in global histone methylation remained when cells were cultured in methionine-free media, indicating that the increased histone methylation did not depend upon any de novo methylation process, but rather was due to the loss of the demethylase protein. Similar increases of H3K4me3 and H3K9me2 were observed in the livers of the mice that were acutely exposed to tungstate via their drinking water. Taken together, our results indicated that tungstate exposure specifically reduced histone demethylase JARID1A and JMJD1A via proteasomal degradation, leading to increased histone methylation.

[Determination of tungsten and cobalt in the air of workplace by ICP-OES].

Objective: To establish the inductively coupled plasma optical emission spectrometry (ICP-OES) method for determination of cobalt and tungsten in the air of workplace. Methods: The cobalt and tungsten were collected by filter membrane and then digested by nitric acid, inductively coupled plasma optical emission spectrometry (ICP-OES) was used for the detection of cobalt and tungsten. Results: The linearity of tungsten was good at the range of 0.01-1 000 µg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.006 7 µg/ml and 0.022 µg/ml, respectively. The recovery was ranged from 98%-101%, the RSD of intra-and inter-batch precision were 1.1%-3.0% and 2.1%-3.8%, respectively. The linearity of cobalt was good at the range of 0.01-100 µg/ml with a correlation coefficient of 0.999 9, the LOD and LOQ were 0.001 2 µg/ml and 0.044 µg/ml, respectively. The recovery was ranged from 95%-97%, the RSD of intra-and inter-batch precision were 1.1%-2.4% and 1.1%-2.9%, respectively. The sampling efficiency of tungsten and cobalt were higher than 94%. Conclusion: The linear range, sensitivity and precision of the method was suitable for the detection of tungsten and cobalt in the air of workplace.

Occupational Exposure to Cobalt and Tungsten in the Swedish Hard Metal Industry: Air Concentrations of Particle Mass, Number, and Surface Area.

Exposure to cobalt in the hard metal industry entails severe adverse health effects, including lung cancer and hard metal fibrosis. The main aim of this study was to determine exposure air concentration levels of cobalt and tungsten for risk assessment and dose-response analysis in our medical investigations in a Swedish hard metal plant. We also present mass-based, particle surface area, and particle number air concentrations from stationary sampling and investigate the possibility of using these data as proxies for exposure measures in our study. Personal exposure full-shift measurements were performed for inhalable and total dust, cobalt, and tungsten, including personal real-time continuous monitoring of dust. Stationary measurements of inhalable and total dust, PM2.5, and PM10 was also performed and cobalt and tungsten levels were determined, as were air concentration of particle number and particle surface area of fine particles. The personal exposure levels of inhalable dust were consistently low (AM 0.15mg m(-3), range <0.023-3.0mg m(-3)) and below the present Swedish occupational exposure limit (OEL) of 10mg m(-3) The cobalt levels were low as well (AM 0.0030mg m(-3), range 0.000028-0.056mg m(-3)) and only 6% of the samples exceeded the Swedish OEL of 0.02mg m(-3) For continuous personal monitoring of dust exposure, the peaks ranged from 0.001 to 83mg m(-3) by work task. Stationary measurements showed lower average levels both for inhalable and total dust and cobalt. The particle number concentration of fine particles (AM 3000 p·cm(-3)) showed the highest levels at the departments of powder production, pressing and storage, and for the particle surface area concentrations (AM 7.6 µm(2)·cm(-3)) similar results were found. Correlating cobalt mass-based exposure measurements to cobalt stationary mass-based, particle area, and particle number concentrations by rank and department showed significant correlations for all measures except for particle number. Linear regression analysis of the same data showed statistically significant regression coefficients only for the mass-based aerosol measures. Similar results were seen for rank correlation in the stationary rig, and linear regression analysis implied significant correlation for mass-based and particle surface area measures. The mass-based air concentration levels of cobalt and tungsten in the hard metal plant in our study were low compared to Swedish OELs. Particle number and particle surface area concentrations were in the same order of magnitude as for other industrial settings. Regression analysis implied the use of stationary determined mass-based and particle surface area aerosol concentration as proxies for various exposure measures in our study.

A hard (metal) case: Value of analytical scanning electron microscopy.

Exposure to hard metal (tungsten carbide) dust is a rare cause of interstitial lung disease. Although most cases have a distinctive morphology known as giant cell interstitial pneumonitis, other patterns have been described as well. In such cases, the true nature of the interstitial process may be difficult to recognize. We present a case with unusual morphological features in which analytical scanning electron microscopy (SEM) was used to detect the presence of tungsten as well as other metallic particles. A combination of careful exposure history and examination by analytical SEM is useful for arriving at the correct diagnosis in such difficult cases.

[Analysis of 2 patients with occupational hard mental lung disease].

OBJECTIVE: We sought to master the clinical characteristics and prognosis of hard mental lung disease, improving this disease's diagnosis and treatment quality. METHODS: We recruited two suspected patients with hard mental lung disease and collected their occupational history, examination results of occupational health, and past medical records. By virtue of laboratory tests, high Kv chest radiography, CT and HRCT of chest, fiberoptic bronchoscopy and ECG examination, diagnostic report was synthesized respectively by respiratory physicians and pathologist from three different agencies. Then the report was submitted to diagnosis organizations of occupational disease, and diagnostic conclusion of occupational disease was drawn after discussion by at least three diagnosticians of occupational disease. RESULTS: We found that both of the two suspected patients were exposed to dusts of hard metal, and length of exposure service ranged from 8 to 9 years. Clinical manifestations were dominated by dry cough, wheezing after activities, and pathological manifestation was characteristic giant cell interstitial pneumonia. The prognosis and outcome of the disease were different. CONCLUSION: According to exact occupational exposure history, clinical manifestations, combined with the results of high Kv chest radiography, CT of chest and pathological manifestation, it can be diagnosed with hard mental lung disease.

Interstitial lung disease related to occupational hard metal exposure: two case reports.

BACKGROUND: Hard metal lung disease (HMLD) is a relatively less known occupational interstitial lung disease, and instances of HMLD resulting from para-occupational exposure are rarely reported. CASE PRESENTATION: This paper presents two cases of interstitial lung disease caused by exposure to hard metal. The first case involves a 37-year-old Taiwanese man who had worked at a grinder station for hard metal materials for 12 years without respiratory protective equipment. He experienced a dry cough and exertional dyspnea, and his chest imaging and pathology findings were consistent with the features of usual interstitial pneumonia. Analysis of his lung tissue revealed the presence of tungsten and cobalt. The second case involves a 68-year-old Taiwanese woman, the mother of the first patient, who had hand-washed her son's workwear. She experienced a dry cough and had similar imaging findings to her son. After her son left his job, they both exhibited improved symptoms and lung functions with nintedanib treatment. These findings suggest a diagnosis of HMLD and interstitial lung disease resulting from para-occupational exposure to hard metal dust. CONCLUSIONS: The diagnosis of HMLD relies on obtaining a detailed occupational exposure history. If HMLD is diagnosed, discontinuing exposing to hard metal dusts can lead to improved lung function.

Tungsten-induced denaturation and aggregation of epoetin alfa during primary packaging as a cause of immunogenicity.

PURPOSE: Following two cases of neutralizing antibodies to epoetin alfa in an investigational clinical study, a small number of individual syringes of two drug product batches were found to contain unusually high levels of aggregation at the end of the clinical trial. METHODS: We undertook an extensive analytical approach to determine the root-cause of the increased aggregation in the affected batches. RESULTS: Soluble tungsten was found in the syringes, most likely derived from the pins used to manufacture the syringes. Spiking of epoetin alfa with sodium polytungstate or an extract of tungsten pins used to manufacture the syringes induced the formation of aggregates, both dimers that appeared to be covalently linked by disulphide bonds as well as higher-order aggregates. Sodium polytungstate had also a strong denaturing effect on the protein. CONCLUSIONS: We propose tungsten-mediated unfolding and aggregation of epoetin alfa in pre-filled syringes as a potential root cause for increased immunogenicity. This finding may be more broadly applicable to this and other classes of therapeutic proteins.

Effect of the Photocatalyst under Visible Light Irradiation in SARS-CoV-2 Stability on an Abiotic Surface.

There is a worldwide attempt to develop prevention strategies against SARS-CoV-2 transmission. Here we examined the effectiveness of tungsten trioxide (WO3)-based visible light-responsive photocatalyst on the inactivation of SARS-CoV-2 under different temperatures and exposure durations. The viral titer on the photocatalyst-coated glass slides decreased from 5.93 ± 0.38 logTCID50 /mL to 3.05 ±. 25 logTCID50/mL after exposure to 3,000 lux of the visible light irradiation for 6h at 20℃. On the other hand, lighting without the photocatalyst, or the photocatalyst-coat without lighting retained viral stability. Immunoblotting and electron microscopic analyses showed the reduced amounts of spike protein on the viral surface after the photocatalyst treatment. Our data suggest a possible implication of the photocatalyst on the decontamination of SARS-CoV-2 in indoor environments, thereby preventing indirect viral spread.

Comparison of free radical generation by pre- and post-sintered cemented carbide particles.

Rapid generation of reactive oxygen species (ROS) may occur in response to cellular contact with metal particles. Generation of ROS by cobalt and/or tungsten carbide is implicated in causing hard metal lung disease (HMD) and allergic contact dermatitis (ACD). In this study, ROS generation and particle properties that influence radical generation were assessed for three sizes of tungsten, tungsten carbide, cobalt, admixture (tungsten carbide and cobalt powders), spray dryer, and post-sintered chamfer grinder powders using chemical (H(2)O(2) plus phosphate buffered saline, artificial lung surfactant, or artificial sweat) and cellular (RAW 264.7 mouse peritoneal monocytes plus artificial lung surfactant) reaction systems. For a given material, on a mass basis, hydroxyl (.OH) generation generally increased as particle size decreased; however, on a surface area basis, radical generation levels were more, but not completely, similar. Chamfer grinder powder, polycrystalline aggregates of tungsten carbide in a metallic cobalt matrix, generated the highest levels of .OH radicals (p < 0.05). Radical generation was not dependent on the masses of metals, rather, it involved surface-chemistry-mediated reactions that were limited to a biologically active fraction of the total available surface area of each material. Improved understanding of particle surface chemistry elucidated the importance of biologically active surface area in generation of ROS by particle mixtures.

[A case of hard metal lung disease in a man who worked as an iron grinder].

The patient was a man who had suffered from repeated pneumothoraces since August 2003, when he was 16 years old. A right pneumothorax was observed at age 21 years, in April 2008. At the same time, a dry cough began to appear and diffuse small nodular shadows in both lung fields were found on a chest X-ray film. Due to worsening symptoms and the chest X-ray findings, a transbronchial lung biopsy was performed in September 2008. Pathological examination showed mural type organization, and large numbers of multinucleated giant cells that were engulfing nucleated cells and had black pigment in their cytoplasm. Giant cell interstitial pneumonia and hard metal lung disease (HMLD) were suspected because of the patient's occupational history as a metal grinder, which included the use of a hard metal tool for three years since August 2005. In an elementary analysis using an electron probe microanalyzer, tungsten was detected in resected lung tissue obtained in April 2008 which confirmed the diagnosis. His symptoms improved after the initiation of corticosteroid therapy, which continued but with a gradual decrease in the dose. In this case, HMLD developed over a relatively short period despite the low level of dust dispersal of a hard-metal tool, perhaps because of a hypersensitivity of the patient to hard metal.

[Giant cell interstitial pneumonia associated with hard metals: a case report and review of the literature].

OBJECTIVE: To highlight the clinical, radiological and pathological characteristics of Objective To highlight the clinical, radiological and pathological characteristics of giant cell interstitial pneumonia (GIP) associated with Hard metals. METHOD: The clinical, radiological and pathological data of a patient with hard metal lung disease confirmed by video-assisted thoracoscopic biopsy of the right lung were presented, and relevant literatures were reviewed. RESULTS: A 30-year-old female patient presented with cough and dyspnea on exertion for more than 40 days. She had worked for grinding tungsten rod, with exposure to metal dusts containing cobalt and tungsten for more than 3 years. Chest radiographs and CT demonstrated bilateral ground-glass attenuations and ill-defined small nodules. Lung function studies showed the mixed type of ventilation dysfunction with a low diffusion capacity (DLCO of 39% of predicted). Lung biopsy specimens showed desquamative interstitial pneumonia like reaction with alveolar macrophages and numerous large multinucleated histiocytes that ingested inflammatory cells in alveolar spaces, which was characteristics of GIP. The lung parenchyma also showed patchy chronic inflammatory-cell infiltrates centered predominantly around the bronchioles and interstitial fibrosis. Considering the exposure history and the histological findings of the lung, the diagnosis of hard metal lung disease and GIP associated with hard metals was made. Her cough, dyspnea, and radiological changes showed marked improvement after corticosteroid therapy and avoidance of further exposure to hard metals. CONCLUSION: GIP is almost pathognomonic for hard metal lung disease. Meticulous history taking on occupational exposure is important for the diagnosis and differential diagnosis of suspected interstitial lung disease.

Metal-induced diffuse lung disease.

The number of metals that are associated with the development of diffuse parenchymal lung disease continues to expand. In addition to lung fibrosis, inhalation of metal particulates can induce a wide range of lung pathology, including reactive airways disease and cancer. This article focuses on diffuse parenchymal diseases resulting from the inhalation of beryllium and cobalt. More is known regarding the immunopathogenesis of beryllium-induced disease than is known for disease induced by any other metal. Chronic beryllium disease (CBD) is a granulomatous lung disorder caused by beryllium exposure in the workplace and is characterized by the accumulation of beryllium-specific CD4 (+) T cells in the bronchoalveolar lavage. Genetic susceptibility markers associated with increased risk have been identified for both CBD and hard metal lung disease. The mechanism for the genetic susceptibility of CBD lies in the ability of certain human leukocyte antigen (HLA)-DP molecules to bind and present beryllium to pathogenic CD4 (+) T cells. Whether the same is true for hard metal lung disease is unknown. In contrast, no HLA allelic association has been identified in nickel allergic subjects. The study of metal-induced lung disease allows the investigation of the relationship between environmental exposure and genetic susceptibility. These studies will enhance our understanding of the immunopathogenesis of metal-induced disease and how exposure to these metals results in irreversible lung fibrosis.

Two-dimensional analysis of elements and mononuclear cells in hard metal lung disease.

RATIONALE: Hard metal lung disease is caused by exposure to hard metal, a synthetic compound that combines tungsten carbide with cobalt as well as a number of other metals. Interstitial lung disease caused by hard metal is uniquely characterized by giant cell interstitial pneumonia. The pathogenesis of hard metal lung disease is unclear. OBJECTIVES: To elucidate the distribution of inhaled hard metal and reactive inflammatory cells in biopsy lung tissue from patients with hard metal lung disease. METHODS: Seventeen patients with interstitial lung disease in which tungsten was detected and five control subjects were studied. Detection and mapping of elements were performed with an electron probe microanalyzer equipped with a wavelength dispersive spectrometer. We immunohistochemically stained mononuclear cells, in tissue samples available from five patients, with anti-human CD4, CD8, CD20, CD68, and CD163 antibodies, and compared the distribution of positive cells with hard metal elements. MEASUREMENTS AND MAIN RESULTS: Thirteen of 17 patients were pathologically diagnosed as having giant cell interstitial pneumonia. Tungsten and cobalt were accumulated in the centrilobular fibrotic lesions, but were never found in the control lungs. CD8+ lymphocytes and CD163+ monocyte-macrophages were distributed predominantly in centrilobular fibrotic lesions around the hard metal elements. CD163+ colocalized with tungsten. Small numbers of CD8+ and CD163+ cells were also immunohistochemically shown in peribronchiolar areas and alveolar walls. CONCLUSIONS: Macrophages may phagocytose inhaled tungsten via CD163 and play an important role in forming the fibrotic lesion of hard metal lung disease with cytotoxic T lymphocytes.