Platy Talc, Asbestos, and Talc Fibers in the Female Genital Tract in Patients with Ovarian Cancer

Introduction/Objective

Recent analyses on human tissue help inform the discussion regarding talc and ovarian cancer, by showing that, in some patients, considerable talc can migrate to multiple organ sites in the pelvic region from perineal application. Recently, we showed that birefringent particles were seen by polarized light microscopy and shown to be talc by scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDS) and/or Raman spectroscopy in surgically resected tissues from patients with ovarian carcinoma and perineal talc exposure. These sites included ovary, cervix, fallopian tube, uterine serosa, and regional lymph nodes. Fibrous talc, with greater carcinogenic potential as determined by the International Agency for Research on Cancer, may be observed in pelvic tissues. Besides ascension through the reproductive tract, particles and fibers may gain entry to pelvic organs by accessing small submucosal lymphatics in the lower part of the tract. Both platy and fibrous talc have an Mg-Si elemental signature, weight % Mg/Si ratio within 5% of the theoretical value of 0.649, and thus are distinguishable from other exogenous substances including the various subtypes of asbestos.

Methods

Tissue-based analytic methods (including in situ SEM, where a paraffin block is examined directly under variable pressure) are critical in the detection of talc and asbestos, particularly since they preserve architecture, and demonstrate talc and/or fibrous particles within their histologic environment; this may help inform exposure origin and pathophysiologic significance.

Results

We reviewed the analytic outcomes of our consultative experience to date. This showed that 180 of 196 patients with a history of perineal talc exposure had birefringent particles seen by light microscopy in surgically resected pelvic tissues, and 82 of 91 had talc confirmed by SEM/EDS. Carcinogenic fibers were found in 28/82 (34%) of these patients, with talc fibers only (19/82 patients, 23%), asbestos (7/82, 9%) or both (2/82, 2%) confirmed by SEM/EDS.

Conclusion

Our study confirms that talc and toxic fibers may be found in human pelvic tissues of talc-exposed patients. Because the SEM/EDS method samples only a small amount of tissue relative to what is in the paraffin block, the finding of exogenous particles by this method typically translates to a high overall particle burden, when scaled mathematically to bulk tissue.

Impact of pathological staging on survival in patients with epithelial mesothelioma treated with extrapleural pneumonectomy

7706

Objective: There is no universally accepted staging system in malignant pleural mesothelioma (MPM). A seventeen-year single institution experience of surgically treating a large epithelial MPM cohort with extrapleural pneumonectomy (EPP) gives insight to the applications and limitations of BWH/ DFCI and AJCC staging systems. Methods: We retrospectivly reviewed 526 consecutive patients with epithelial MPM who were surgically explored at our institution since 1988 with intent to perform EPP. Pathologic diagnoses of mesothelioma were confirmed and clinicopathologic data were recorded. Kaplan-Meyer survival from diagnosis was calculated. Those who underwent EPP were staged using BWH / DFCI (J Thorac Cardiov Surg 117:5463;1999) and AJCC (6th Edition) criteria. Operative deaths were included in the analysis and patients received varied adjuvant regimens. Results: Of 526 patients explored for potential EPP, 53 (10%) underwent alternative pleurectomy and 55 (11%) were unresectable. The remaining 418 (79%) underwent EPP. Of these, 307 (73%) were male. Median age at diagnosis was 57.9 years (17–78). Operative mortality was 5%. Median follow-up was 16 months and 23% of observations were censored. Overall median, 1-yr, 3-yr and 5-yr survival was: 18.9 mo., 68.8%, 26.3%, and 13.9%. The table below presents Kaplan-Meyer survival by stage. Conclusions: 1) Both pathological staging systems stratify survival in this cohort, although each system is limited in that a majority of patients are classified as stage 3. 2) BWH / DFCI criteria identify more stage 1–2 patients with favorable prognosis, 164 (39%) vs 46 (11%). 3) AJCC criteria classify more patients to stage 4, 76 (18%) vs 4 (1%), but appear to identify some patients with relatively favorable prognosis. 4) Selected criteria from both systems might be combined to optimally stratify patients with epithelial MPM undergoing EPP.

No significant financial relationships to disclose.

[Table: see text]

Acute pulmonary and hematological effects of two types of particle surrogates are influenced by their elemental composition

Several epidemiological studies have consistently demonstrated significant associations between ambient levels of particulate matter and lung injury and cardiovascular events with increased morbidity and mortality. Particle surrogates (PS), such as residual oil fly ash (ROFA), have been widely used in experimental studies aimed at characterizing the mechanisms of particle toxicity. Since PS composition varies depending on its source, studies with different types of PS may provide clues about the relative toxicity of the components generated by high-temperature combustion process. In this work, we have studied the effects of nasal instillation of increasing doses of different PS in mice: saline, carbon, and two types of particle surrogates. PS type A (PSA) was the ROFA collected from the waste incinerator of our university hospital; PS type B (PSB) was collected from the electrostatic precipitator of a large steel company and thus had an elevated metal content. After 24h, we analyzed hematological parameters, fibrinogen, bronchoalveolar lavage, bone marrow, and pulmonary histology. Nasal instillation of the two types of PS-induced leucopenia. PSB elicited a greater elevation of plasma fibrinogen levels. Bone marrow and pulmonary inflammatory changes were more intense for PSA. We concluded that the PS composition modulates acute inflammatory changes more significantly than the mass for these two types of PS.

Differential ability of transition metals to induce pulmonary inflammation

Transition metals are components of airborne particles and have been implicated in adverse health effects. The relative inflammatory potential of these metals is usually inferred from separate studies that focus on only one or a few individual metals. Comparisons of relative potency among several metals from these separate studies can be difficult. In one comprehensive study, we measured the pulmonary effects of equimolar doses of six metals in soluble form. Our purpose was to compare inflammatory potential and pulmonary toxicity among individual transition metals. Rats received saline, 0.1 or 1.0 micromol/kg of vanadium, nickel, iron(II), copper, manganese, or zinc as sulfates. Bronchoalveolar lavage (BAL) was performed at 0, 4, 16, or 48 h postinstillation. All treatments except V showed increased lactate dehydrogenase activity in BAL fluid; Cu- and Ni-exposed animals had the highest levels. Protein levels in BAL fluid were more than five times higher in Cu-exposed animals compared to other metal treatments at 16 and 48 h. At the 0.1 micromol/kg dose, only Cu induced significant neutrophilia at 16 and 48 h. For the 1.0 micromol/kg dose, all metals tested induced significant neutrophilia, with mean neutrophil numbers for Cu and Mn significantly higher compared to the other metals. At 48 h, neutrophil numbers were still elevated in all metal exposures. Only Mn caused substantial eosinophilia. At the 1.0 micromol/kg dose, only Cu induced macrophage inflammatory protein-2 (MIP-2) mRNA at 4 h. By 48 h, induction of MIP-2 mRNA was observed for all metal exposures except Cu, which subsequently returned to baseline levels. On an equimolar basis, Cu was the most proinflammatory metal, followed by Mn and Ni, while V, Fe(II), and Zn induced similar levels of inflammation. Overall, there were many similarities in the pulmonary responses of the metals we tested. However, we also observed divergent, metal-specific responses. These differential responses suggest that metals induce pulmonary inflammation by differing pathways or combinations of signals.

Transmission electron microscopy of intracellular particles of polyethylene from joint replacement prostheses: size distribution and cellular response

The objectives of this transmission electron microscopy study of peri-implant tissues retrieved at revision arthroplasty were to (1) determine the size distribution of intracellular polyethylene particles, and (2) assess the cellular response to phagocytosed polyethylene particles as revealed by the condition of the cellular organelles. The frequency distributions of intracellular polyethylene particle sizes for 15 cases of total hip replacement showed that more than 75% of the particles had lengths of less than 0.5 microm. More than 90% of the particles were less than 1.0 microm in size. In comparison, the frequency distribution for the particles in cellscomprising tissue retrieved from three total knee replacement prostheses showed that only 43% of the particles were less than 0.5 microm in length and 72% were less than 1 microm in size. There was no statistically significant difference in the mean particle length between the specimens from the hip and knee patients. The majority of the cells containing polyethylene were without signs of degeneration. The cytoplasmic and nuclear membranes were intact. Several electron lucent voids which once contained polyethylene particles were seen surrounded by several healthy appearing mitochondria, which displayed sharp membranes and intact cristae. There were no signs of a cytotoxic response to polyethylene at the ultrastructural level.

Ultrafine particles in human lung macrophages

As knowledge about size dependency of particle toxicity continues to grow, attention has been focused on ultrafine particles (i.e., < 0.1 microm in diameter). In recent studies with rats, investigators learned that ultrafine particles likely have greater pulmonary toxicity than larger particles, and it is possible that exposure to, and accumulation of, these particles in the human lung may be associated with adverse respiratory health effects. As part of an ongoing study, the authors performed bronchoalveolar lavage in 14 healthy current nonsmokers to investigate the extent to which ultrafine particles were present in lung macrophages. In addition, 10 of the 14 subjects performed pulmonary function tests. Eleven of the 14 subjects were utility workers, and 3 were nonmaintenance employees of a university. The authors used a Zeiss CEM902 electron microscope to study macrophages isolated from bronchoalveolar lavage fluid. Morphometric quantification revealed ultrafine particles in lung macrophages of all 14 volunteers; the average number of ultrafine particles/microm3 cytoplasm per cell (UFavg) ranged from 34 to 231 (mean = 95, standard deviation = 54). Regression analysis showed that the UFavg was associated inversely with percent predicted forced expiratory volume in 1 second (FEV1.0) (beta = -1.2 percent predicted FEV1.0/10 ultrafine particles x microm3 cytoplasm per cell [standard error = 0.45, p = .031). The demonstration of ultrafine particles in all 14 subjects, independent of occupational exposure, suggests that there is environmental exposure to ultrafine particles. The negative association between the number of ultrafine particles and ventilatory function demonstrates a need for further investigation into the pulmonary health effects of ultrafine particles.

Endocytosis of ultrafine particles by A549 cells

Alveolar epithelium's capacity to ingest inhaled ultrafine particles is not well characterized. The objectives of this study were to use an in vitro model of type II lung epithelium and evaluate the cells' ability to take up ultrafine particles (titanium dioxide [TiO(2)], 50 nm diameter). The human epithelial cell line A549 was grown on aclar substrates and exposed to 40 microg/ml TiO(2) particles for 3, 6, and 24 h before imaging with energy-filtering transmission electron microscopy. Elemental mapping and electron energy loss spectroscopy were used to colocalize Ti/O with electron-dense particles. Particle endocytosis was compared in A549 cells with and without pretreatment with cytochalasin D (cyto D) (2 microg/ml). After 3 h of TiO(2) exposure, cells internalized aggregates of the ultrafine particles which were observed in cytosolic, membrane-bound vacuoles. After 24 h of exposure there were considerably more intracellular aggregates of membrane-bound particles, and aggregated particles were also enmeshed in loosely and tightly packed lamellar bodies. Throughout 24 h of exposure a preponderance of particles remained associated with the free surface of the cells and were not internalized. The majority of membrane-bound vacuoles contained aggregates of particles and only occasionally did they contain as few as two or three particles, despite the use of several different approaches to assure the possibility for individual particles to be ingested and detected. There was morphologic evidence of microfilament disturbance, but no evidence of a decrease in internalized particles in cells pretreated with cyto D. Thus, this model of type II epithelium is able to internalize aggregates of ultrafine particles.

Inhaled concentrated ambient particles are associated with hematologic and bronchoalveolar lavage changes in canines

Pulmonary inflammatory and hematologic responses of canines were studied after exposure to concentrated ambient particles (CAPs) using the Harvard ambient particle concentrator (HAPC). For pulmonary inflammatory studies, normal dogs were exposed in pairs to either CAPs or filtered air (paired studies) for 6 hr/day on 3 consecutive days. For hematologic studies, dogs were exposed for 6 hr/day for 3 consecutive days with one receiving CAPs while the other was simultaneously exposed to filtered air; crossover of exposure took place the following week (crossover studies). Physicochemical characterization of CAPs exposure samples included measurements of particle mass, size distribution, and composition. No statistical differences in biologic responses were found when all CAPs and all sham exposures were compared. However, the variability in biologic response was considerably higher with CAPs exposure. Subsequent exploratory graphical analyses and mixed linear regression analyses suggested associations between CAPs constituents and biologic responses. Factor analysis was applied to the compositional data from paired and crossover experiments to determine elements consistently associated with each other in CAPs samples. In paired experiments, four factors were identified; in crossover studies, a total of six factors were observed. Bronchoalveolar lavage (BAL) and hematologic data were regressed on the factor scores. Increased BAL neutrophil percentage, total peripheral white blood cell (WBC) counts, circulating neutrophils, and circulating lymphocytes were associated with increases in the aluminum/silicon factor. Increased circulating neutrophils and increased BAL macrophages were associated with the vanadium/nickel factor. Increased BAL neutrophils were associated with the bromine/lead factor when only the compositional data from the third day of CAPs exposure were used. Significant decreases in red blood cell counts and hemoglobin levels were correlated with the sulfur factor. BAL or hematologic parameters were not associated with increases in total CAPs mass concentration. These data suggest that CAPs inhalation is associated with subtle alterations in pulmonary and systemic cell profiles, and specific components of CAPs may be responsible for these biologic responses.

Inhaled concentrated ambient particles are associated with hematologic and bronchoalveolar lavage changes in canines

Pulmonary inflammatory and hematologic responses of canines were studied after exposure to concentrated ambient particles (CAPs) using the Harvard ambient particle concentrator (HAPC). For pulmonary inflammatory studies, normal dogs were exposed in pairs to either CAPs or filtered air (paired studies) for 6 hr/day on 3 consecutive days. For hematologic studies, dogs were exposed for 6 hr/day for 3 consecutive days with one receiving CAPs while the other was simultaneously exposed to filtered air; crossover of exposure took place the following week (crossover studies). Physicochemical characterization of CAPs exposure samples included measurements of particle mass, size distribution, and composition. No statistical differences in biologic responses were found when all CAPs and all sham exposures were compared. However, the variability in biologic response was considerably higher with CAPs exposure. Subsequent exploratory graphical analyses and mixed linear regression analyses suggested associations between CAPs constituents and biologic responses. Factor analysis was applied to the compositional data from paired and crossover experiments to determine elements consistently associated with each other in CAPs samples. In paired experiments, four factors were identified; in crossover studies, a total of six factors were observed. Bronchoalveolar lavage (BAL) and hematologic data were regressed on the factor scores. Increased BAL neutrophil percentage, total peripheral white blood cell (WBC) counts, circulating neutrophils, and circulating lymphocytes were associated with increases in the aluminum/silicon factor. Increased circulating neutrophils and increased BAL macrophages were associated with the vanadium/nickel factor. Increased BAL neutrophils were associated with the bromine/lead factor when only the compositional data from the third day of CAPs exposure were used. Significant decreases in red blood cell counts and hemoglobin levels were correlated with the sulfur factor. BAL or hematologic parameters were not associated with increases in total CAPs mass concentration. These data suggest that CAPs inhalation is associated with subtle alterations in pulmonary and systemic cell profiles, and specific components of CAPs may be responsible for these biologic responses.

Mechanisms of morbidity and mortality from exposure to ambient air particles

The studies reported here assessed pathophysiologic mechanisms that result from exposure to concentrated ambient particles (CAPs) in animals with and without cardiopulmonary compromise. These studies were carried out to determine the biologic plausibility of epidemiologic observations of increases in particulate air pollution associated with increases in human morbidity and mortality. Dogs were exposed two at a time to CAPs or filtered air via tracheostomy for six hours per day on three consecutive days. The electrocardiogram (ECG) and breathing pattern were recorded continuously, and indicators of inflammation were also assessed. In one experimental design, normal dogs were exposed in pairs to CAPs and subsequently to filtered air or to filtered air and subsequently CAPs (the double CAPs/double sham design). Comparisons were made between the CAPs measurements and each dog's own sham responses. In another design, one dog was exposed to CAPs while the chambermate received a sham exposure; these experiments were followed by crossover of the protocol the subsequent week (the crossover design). Comparisons were made between the CAPs exposure and both the chambermate's sham and each dog's own sham responses. The crossover experiments were conducted in normal animals and in animals who had undergone balloon occlusion of the left anterior descending (LAD) coronary artery to induce myocardial compromise. The effects of CAPs in animals with induced chronic bronchitis were part of the original specific aims; because these studies were not fully pursued, the results are presented only in Appendix A. In normal dogs, analyses of all double CAPs and crossover studies revealed low frequency (LF) and high frequency (HF) powers for heart rate variability (HRV) that were significantly higher for CAPs exposure compared to sham exposure. Variation in day-to-day exposure concentrations, aerosol composition, and pathophysiologic responses were also found. The crossover design, continuous measures of aerosol mass, and biologic responses were incorporated in the development of a statistical model that allowed isolation of changes associated with CAPs from changes due to animal variations. Comparison of individual exposures with this model revealed a range from no response in any measured parameter to statistically significant changes in cardiac autonomic balance, pulmonary air flow, and breathing pattern. On days in which dogs showed statistically significant changes in responses, the findings were consistent in both cardiac and respiratory parameters. Days associated with significant increases in LF and HF HRV, LF/ HF HRV ratio, and heart rate standard deviation (HR SD) were also associated with decreases in average heart rate. These same days had decreases in respiratory frequency, tidal volume, minute volume, and peak flows with corresponding increases in respiratory cycle times and enhanced pause (Pauenh), a measure of bronchoconstriction. These cardiac and respiratory changes suggest an effect mediated via both the sympathetic nervous system and the vagus nerve. Alternatively, days associated with increased heart rate had decreases in the HR SD; decreases or no change in HF and LF HRV; increases in respiratory flows and volumes; and decreases in breathing cycle times, all suggesting only sympathetic nervous system mediation. When all data from the crossover design experiments were assessed with this model, the heart rate and respiratory rate were significantly decreased in relation to both cumulative and actual exposure and the LF HRV, LF/HF HRV ratio, HR SD, and all other respiratory parameters were significantly increased (p < 0.0001 for all). When cardiac data were grouped by days in which the air mass trajectory came from the north or northwest (versus west, south, east, or northeast), significant increases in HR SD and HF HRV and significant decreases in average heart rate were associated with the northwest trajectory. (ABSTRACT TRUNCATED)

Urban air particulate inhalation alters pulmonary function and induces pulmonary inflammation in a rodent model of chronic bronchitis

Epidemiological studies have reported increased morbidity in human populations following inhalation of elevated levels of urban particulate matter. These responses are especially prevalent in populations with chronic obstructive pulmonary diseases, including chronic bronchitis. Toxicological studies have reported altered pulmonary function and increased pulmonary inflammation following particulate inhalation in the laboratory setting. However, most of these studies have utilized artificial particles that may not accurately mimic outdoor air pollutant conditions. Few studies have utilized actual urban air particle samples in inhalation studies. In the present study, the effects of inhaled concentrated urban air particulates on pulmonary function and pulmonary inflammation are addressed. Normal rats and rats with chronic bronchitis induced by approximately 200 ppm SO(2) for 6 wk were subsequently subjected to filtered air or concentrated air particles (CAPs). Twelve rats per group in 4 groups (48 rats total) were exposed for 5 h/day for 3 consecutive days. The CAPs aerosol levels were 206, 733, and 607 microg/m(3) (MMAD = 0.18 microm, sigma(g) = 2.9) on days 1, 2, and 3, respectively. Following the final day of exposure, pulmonary function parameters, including peak expiratory flow (PEF), tidal volume (TV), respiratory frequency (RF), and minute volume (MV), were measured and compared to preexposure baseline levels. Twenty-four hours following the final day of exposure, bronchoalveolar lavage was performed for total cell counts, differential cell counts, and total lavage protein levels. Pulmonary responses to CAPs in chronic bronchitic animals indicated a significant increase in tidal volume as well as peak expiratory flow. In CAPs-exposed animals without underlying bronchitis, significantly increased tidal volume was observed. Significant pulmonary inflammation was observed in the CAPs-exposed animals, particularly those with chronic bronchitis. Significant increases in neutrophils, lymphocytes, and total lavage protein were observed. These results suggest two distinct mechanistic responses to inhaled particles: a stress-type pulmonary function response marked by increases in flow and volume, that is, deeper breathing; and acute pulmonary inflammation marked by cellular influx, particularly neutrophils. From these data it is concluded that inhaled urban air particles alter pulmonary breathing parameters and increase pulmonary inflammation.

Anatomic localization of 24- and 96-h particle retention in canine airways

Long-term retention of particles in airways is controversial. However, precise anatomic localization of the particles is not possible in people. In this study the anatomic location of retained particles after shallow bolus inhalation was determined in anesthetized, ventilated beagle dogs. Fifty 30-cm(3) boluses containing monodisperse 2.5-micron polystyrene particles (PSL) were delivered to a shallow lung depth of 81-129 cm(3). At 96 h before euthanasia, red fluorescent PSL were used; at 24 h, green fluorescent PSL and (99m)Tc-labeled PSL were used. Clearance of (99m)Tc-PSL was measured during the next 24 h. Sites of particle retention were determined in systematic, volume-weighted random samples of microwave-fixed lung tissue. Precise particle localization and distribution was analyzed by using gamma counting, conventional fluorescence microscopy, and confocal microscopy. Within 24 h after shallow bolus inhalation, 50-95% of the deposited (99m)Tc-PSL were cleared, but the remaining fraction was cleared slowly in all dogs, similar to previous human results. The three-dimensional deposition patterns showed particles across the entire cross-sectional plane of the lungs at the level of the carina. In these locations, 33 +/- 9.9% of the retained particles were found in small, nonrespiratory airways (0.3- to 1-mm diameter) and 49 +/- 10% of the particles in alveoli; the remaining fraction was found in larger airways. After 96 h, a similar pattern was found. These findings suggest that long-term retention in airways is at the bronchiolar level.

Regulation of macrophage inflammatory protein-2 gene expression by oxidative stress in rat alveolar macrophages

Chemokines are important mediators in the development of inflammation. Our previous work demonstrated that an oxidative stress can up-regulate mRNA expression of a CC chemokine macrophage inflammatory protein (MIP)-1alpha in rat alveolar macrophages. In the present study, we further investigate whether an oxidative stress can regulate the gene expression of a related CXC chemokine MIP-2, involved in both neutrophil chemotaxis and activation. A rat alveolar macrophage cell line (NR8383) was exposed to 10 microg/ml bacterial lipopolysaccharide (LPS) and MIP-2 mRNA levels dramatically increased after 4 hr of stimulation. This increase by LPS was attenuated by co-treatment with the antioxidants N-acetylcysteine and dimethylsulphoxide, suggesting that the induction of MIP-2 mRNA is mediated via the generation of reactive oxygen species. To assess directly the role of oxidative stress on regulation of MIP-2 mRNA expression, macrophages were exposed to H2O2. MIP-2 mRNA levels had significantly increased after 1 hr exposure to 0.5 mm H2O2, were maximally increased after 4 hr and decreased after 6 hr. Co-treatment of macrophages with the transcriptional inhibitor actinomycin D eliminated the H2O2-induction of MIP-2 mRNA, implicating a role for transcriptional activation in increased expression of MIP-2. Genomic cloning of the rat MIP-2 gene 5'-flanking region has identified a consensus nuclear factor-kappaB (NF-kappaB) binding site. Gel-mobility shift assays revealed NF-kappaB binding to the MIP-2 promoter/enhancer sequence was induced by H2O2. LPS treatment for 4 hr also significantly activated NF-kappaB binding, which could also be attenuated by pretreatment with N-acetylcysteine at the doses that reduced MIP-2 mRNA expression. The half-life of MIP-2 mRNA transcripts was also increased by H2O2 treatment. These observations indicate that MIP-2 gene expression is subject to both transcriptional and post-transcriptional control in response to an H2O2 oxidative stress.

Health effects of sulfur-related environmental air pollution. V. Lung structure

The lungs of 8 male beagle dogs were examined morphologically and morphometrically after exposure for 13 mo to a respirable sulfur(IV) aerosol at a mass concentration of 1.53 mg m(-3) (16.5 h/day), and to an acidic sulfate aerosol carrying 15.2 micromol m(-3) hydrogen ions into the lungs (6 h/day). An additional eight dogs served as unexposed controls. Standard morphometric analyses of both the surface epithelia of the conducting airways and the alveolar region were performed. These analyses showed no difference between the exposure group and control group. However, there was a tendency to an increase in the volume density of bronchial glands in the exposure group. Five of eight exposed animals showed thickened ridges (knob-like structures) at the entrance to alveoli in the alveolar duct and alveolar sac. Transmission electron microscopy revealed that the thickening was mainly due to type II cell proliferation. As the previous experiment using sulfite aerosol only showed no alterations in the proximal alveolar regions, the changes observed may be considered as effects of acidic sulfate aerosol alone or in combination with sulfite. These findings suggest that sulfur aerosols have the potential to induce epithelial alterations in the proximal alveolar region, which is a primary target for air pollutants.

Mediating phosphorylation events in the vanadium-induced respiratory burst of alveolar macrophages

Occupational exposure by inhalation to vanadium-containing particles such as residual oil fly ash results in respiratory tract inflammation. This inflammation, characterized by abundant neutrophilia, appears to be initiated by alveolar macrophages (AMs) encountering particles and the subsequent release of proinflammatory cytokines. Intracellular signaling events in these cells in response to particles or their components are largely unknown. We investigated two immediate responses of AMs to vanadium exposure in vitro, the production of reactive oxygen intermediates (ROI) or respiratory burst (RB), and the tyrosine phosphorylation of cellular proteins. Macrophages exposed in vitro to 100 microM vanadyl chloride/1 microCi 48V incorporated 8.3% of the metal after 30 min. Exposure of AMs to increasing concentrations of sodium metavanadate resulted in a dose-dependent increase in production of ROI as measured by dichlorofluorescin oxidation. The lowest dose yielding a significant response was 50 microM, whereas 1000 microM increased RB activity by 173%. NADPH oxidase inhibitors deoxy-D-glucose (100 mM) and diphenylene iodonium (25 microM) reduced the metavanadate-induced RB by 62 and 71%, respectively, implicating NADPH oxidase as the primary cellular source of ROI. Enhanced cerium chloride oxidation in response to metavanadate localized to the plasma membrane consistent with increased NADPH oxidase activity. Pretreatment of AMs with the epidermal growth factor receptor inhibitor, tryphostin B50 (10 microM), reduced the metavanadate-induced RB, but did not influence overall tyrosine phosphorylation. Metavanadate and H2O2 exposure greatly increased overall tyrosine phosphorylation, yielding a similar but distinguishable pattern of phosphorylation in these cells. These observations demonstrate that in vitro metavanadate exposure regulates two distinct, yet related intracellular signaling pathways important in initiating inflammatory responses in these cells: (1) activation of the NADPH oxidase complex with subsequent increased ROI synthesis, and (2) enhanced tyrosine phosphorylation of cellular proteins.

Functional characterization of recombinant rat macrophage inflammatory protein-1 alpha and mRNA expression in pulmonary inflammation

Chemokines are important inflammatory mediators that function by activating and recruiting leukocytes to an inflamed tissue. We have recently cDNA cloned the rat chemokine macrophage inflammatory protein-1 alpha (MIP-1 alpha) (1). In the present study, we characterize the biological function of recombinant MIP-1 alpha protein and describe expression of its mRNA both in vitro and in a rat model of lung inflammation. In vitro rat rMIP-1 alpha protein was chemotactic for both polymorphonuclear leukocytes (PMNs) and macrophages with maximal activity at 50 nM for both cell types. In in vivo studies, we found that intratracheal instillation of 1 and 5 micrograms of rMIP-1 alpha resulted in a significant (P < 0.05) influx of cells, primarily monocytes/macrophages, into the airspace of the lungs after 6 h. Mean numbers of lavagable PMNs were not elevated significantly (P < 0.05) for either dose of MIP-1 alpha. As a model of inflammation, rats were intratracheally instilled with 0.1 mg/kg bacterial lipopolysaccharide (LPS). Bronchoalveolar lavage (BAL) was performed 3 h later. Instillation of LPS resulted in an acute neutrophilia, but no significant change in lavagable macrophages. BAL cells from control animals (saline instilled) displayed no basal mRNA expression of either MIP-1 alpha or MIP-2 (positive control). In contrast, both MIP-1 alpha and MIP-2 mRNA levels increased markedly in BAL cells from rats instilled with LPS. The rat alveolar macrophage cell line (NR8383) also showed increased MIP-1 alpha mRNA levels in response to LPS (10 micrograms/ml) with a maximal increase after 6-8 h. The induction of MIP-1 alpha mRNA expression by LPS in NR8383 cells was attenuated by cotreatment with the antioxidants N-acetylcysteine and dimethylsulfoxide, suggesting that the induction of MIP-1 alpha mRNA by LPS is mediated via the generation of reactive oxygen species. We conclude that MIP-1 alpha is a potent chemoattractant for macrophages in vivo, and its mRNA expression in macrophages and BAL cells in response to inflammatory stimuli suggests a fundamental role in acute pulmonary inflammation.

The elephant's respiratory system: adaptations to gravitational stress

Elephants have had to adapt to gravitational stresses imposed on their very large respiratory structures. We describe some unusual features of the elephant's respiratory system and speculate on their functional significance. A distensible network of collagen fibers fills the pleural space, loosely connects lung to chest wall but appears not to constrain lung-chest wall movements. Myriad spaces within the network and its rich supply of capillaries suggest effective local sources and sinks for pleural fluid that may replace the gravity-dependent flows of smaller mammals. The lung is partitioned into approximately equal to 1 cm3 parenchymal units by a system of thick, elastic septa that ramify throughout the lung from origins on the lung's elastic external capsule. Parenchymal units suspended upon the elastic septal system protect dependent alveoli from compression, thereby reducing the usual gravitational gradient of lung expansion. Intra-pulmonary airways are devoid of cartilage, instead they appear to derive resistance to collapse from tethering forces of the attached septa.

Vanadium-induced chemokine mRNA expression and pulmonary inflammation

Occupational exposure to vanadium is common in petrochemical, mining, steel, and utilities industries and results in toxic effects largely confined to the respiratory system. Vanadium exposure has been associated with inflammatory changes in the upper and lower respiratory tracts in addition to changes in pulmonary function. We investigated the abilities of several vanadium compounds to increase mRNA levels for selected cytokines in bronchoalveolar lavage (BAL) cells and also to induce pulmonary inflammation. Rats (200-250 g) were intratracheally instilled with either sodium metavanadate (NaVO3), vanadyl sulfate (VOSO4), vanadium pentoxide (V2O5) at several concentrations, or vehicle alone. Pulmonary inflammation was assessed by cytologic analysis of cells recovered from the respiratory tract (1 hr to 10 days postexposure). All three vanadium compounds were capable of inducing pulmonary inflammation in a dose-dependent manner. Neutrophil influx was greatest following exposure to VOSO4 (peaked at approximately 40% of cell population) and lowest following exposure to V2O5 (peaked at approximately 20 %). Significant neutrophil influx was detected as early as 4 hr following the instillation of NaVO3 and VOSO4 but not until 24 hr upon exposure to V2O5. The VOSO4-induced inflammatory response persisted longer (5 days) than that induced by NaVO3 and V2O5. Analysis of inflammatory cytokine mRNA expression closely followed these cytologic observations. Levels of mRNA for macrophage inflammatory protein-2 (MIP-2) and KC, considered the principal neutrophil chemotactic factors expressed in the rat, were rapidly induced as early as 1 hr following exposure, continued to be expressed throughout 48 hr, and were low but detectable at 5 and 10 days. NaVO3 and VOSO4, both very soluble forms of vanadium, tended to induce pulmonary inflammation and inflammatory cytokine mRNA expression more rapidly and more intensely than the less soluble form, V2O5. Analysis of KC mRNA expression in BAL cells 24 hr after instillation of NaVO3 by PCR in situ hybridization confirmed the increase in KC mRNA levels and indicated that alveolar macrophages have the highest expression level observed. Vanadium content of lavage fluid, BAL cells, and lung indicated rapid clearance of the metal from the lung surface and substantial accumulation by BAL cells and lung tissue. The rapid expression of MIP-2 and KC mRNA in BAL cells prior to the observed neutrophilia implicate them as important in the initiation of inflammation.

Regulation of macrophage inflammatory protein-1alpha mRNA by oxidative stress

Accumulation of inflammatory cells within the lung has been implicated in oxidative injury. Recruitment of these cells to a tissue site is a complex process that depends in part upon the local expression of appropriate proinflammatory chemokines. Macrophage inflammatory protein-1alpha (MIP-1alpha), a member of the CC subfamily of chemokines, has been shown to contribute to monocyte/macrophage and neutrophil chemotaxis and activation. Our previous work demonstrated that MIP-1alpha mRNA expression in macrophages is induced by bacterial endotoxin. The objective of this study was to test the hypothesis that an oxidative stress alone may trigger expression of MIP-1alpha mRNA in macrophages and to determine the mechanism leading to increased expression. A rat alveolar macrophage cell line (NR8383) was exposed to H2O2 or menadione (2-methyl-1,4-naphthoquinone (MQ)), a quinone compound that undergoes redox cycling and generates reactive oxygen species continuously. Steady-state mRNA levels encoding MIP-1alpha were markedly increased (3-fold) in these cells after 1 h of exposure to 0.5 mM H2O2, remained higher than control levels after 4 h, and decreased after 6 h. Similarly, MQ (25 or 50 microM) caused a significant increase of MIP-1 alpha mRNA with a maximal induction after 4 h of exposure (5-fold). Both H2O2 and MQ-induced up-regulation of MIP-1 alpha mRNA was suppressed by co-treatment with N-acetylcysteine, a synthetic antioxidant. Co-treatment with actinomycin D reduced the MQ induction of MIP-1alpha mRNA to a greater extent than the H2O2-induced increase. Transcription of the MIP-1alpha gene was increased by exposure to both H2O2 and MQ. H2O2 treatment also induced a marked increase of the MIP-1alpha mRNA half-life, indicating post-transcriptional stabilization. These observations indicate that an oxidative stress can regulate MIP-1alpha mRNA expression by two distinct mechanisms: transcriptional activation of the MIP-1alpha gene and post-transcriptional stabilization of MIP-1alpha mRNA.

Imaging biliary lipid secretion in the rat: ultrastructural evidence for vesiculation of the hepatocyte canalicular membrane

Physical-chemical and biological studies of hepatic bile suggest that biliary phospholipid molecules are secreted as unilamellar vesicles. Systematic ultrastructural studies of bile canaliculi were undertaken to visualize this event. Liver tissue was obtained from normal adult male rats (control), from bile salt-depleted rats (by overnight biliary diversion), and from depleted rats infused intravenously with a hydrophilic-hydrophobic congener series of common taurine-conjugated bile salts. Livers were fixed in situ either by modified chemical methods or by ultrarapid cryofixation. In control rats, chemical fixation revealed unilamellar vesicles 63 +/- 17 (+/- SD) nm in diameter, mostly free within canalicular lumena. Vesicles were infrequent in canaliculi of bile salt-depleted rats, but were present in canaliculi of rats infused with taurocholate. In cryofixed liver tissue, vesicles 67 +/- 13 nm in diameter were observed in canaliculi of control rats and bile-salt depleted rats infused with common bile salts. The majority of these vesicles were affixed to the luminal side of the canalicular membrane. The average number of vesicles per bile canaliculus was in agreement with that estimated on the basis of biliary phospholipid secretion rates, mean vesicle size, and area of close-packed phosphatidylcholine molecules. By immunoelectron microscopy, canalicular vesicles were free of actin and of a 100 kDa canalicular membrane protein. We conclude that biliary phospholipid molecules are secreted from hepatocytes into bile canalicular lumena as unilamellar vesicles approximately 63-67 nm in average diameter. We postulate that this secretion mechanism involves lumenal bile salt-induced vesiculation of lipid microdomains in the exoplasmic hemileaflet of the canalicular membrane.

Molecular cloning and posttranscriptional regulation of macrophage inflammatory protein-1 alpha in alveolar macrophages

Macrophage inflammatory protein-1 alpha (MIP-1 alpha) belongs to the "chemokine" superfamily of chemoattractant pro-inflammatory cytokines. MIP-1 alpha is chemotactic for monocytes and neutrophils and thus, plays an important role in initiation and control of inflammation. We have isolated and sequenced a cDNA clone encoding rat MIP-1 alpha. This 0.75 kb cDNA includes a single open reading frame of 92 amino acids. Expression of MIP-1 alpha mRNA was characterized in NR8383, a rat alveolar macrophage cell line (RAM). In resting RAM cells, MIP-1 alpha mRNA decayed rapidly, with a half life of less than 2 hours. Lipopolysaccharide (LPS) treatment of RAM cells resulted in a dose-dependent increase in MIP-1 alpha steady state mRNA expression. The induction of MIP-1 alpha mRNA by LPS was partially the result of mRNA stabilization, as half life increased to over 6 hours.

Chronic bronchitis alters the pattern of aerosol deposition in the lung

Knowledge of the local and regional doses of inhaled particulates is crucial for inhalation therapy and for understanding the progression of pulmonary disease. We studied the deposition pattern of radioactively tagged particles in rats with chronic bronchitis. Rats were exposed to sulfur dioxide (SO2; 236 +/- 14 ppm) for 5 h/d, 5 d/wk for 7 wk to produce chronic bronchitis (CB). Control rats were exposed to room air. The control animals gained 85% more weight over the 7-wk period than did the CB rats. Five control and five CB rats were then exposed for 30 min to an insoluble 99mTc-labeled aerosol. The animals were killed within 5 min after the exposure period. The lungs were excised, dried at total lung capacity (TLC), and sliced into 1 mm sections. The distribution of the radiolabeled particles retained in the lungs was determined in two ways. First, autoradiographs were made of the distribution of the radioactivity throughout a lung slice. Autoradiographs were quantified by image analysis to determine the amount of radioactivity (relative density of the film) associated with airway versus parenchyma (ratio of airway to parenchyma density). The lung slices were then dissected into pieces, the weight and radioactivity content of each piece was measured, and its evenness index (EI) was calculated. This type of analysis enables the homogeneity of particle deposition throughout the lungs to be assessed. If deposition were totally uniform, the average EI would be 1.0 with an SD = 0. The total amount of radioactivity retained in the lungs was similar in control and CB rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural localization of a fluorinated bile salt in hepatocytes

BACKGROUND

Interactions of bile salts with hepatocellular organelles are critical for the formation of bile, yet these interactions remain poorly characterized. We present a novel approach for visualizing bile salts at the ultrastructural level within hepatocytes, using a unique fluorinated bile salt conjugate and electron energy loss spectroscopy.

EXPERIMENTAL DESIGN

Isolated rat hepatocytes were incubated for 5 and 20 minutes with the 2-fluoro-beta-alanine (FBAL) N-acyl amidate conjugate of cholic acid (C-FBAL, 50 microM). FBAL is a byproduct of hepatic 5-fluorouracil catabolism, and when conjugated to cholic acid is excreted into bile in a manner similar to the naturally occurring N-acyl amidates of bile salts. Cells were subjected to rapid cryofixation and automated freeze-drying followed by vapor-phase fixation using the LifeCell system, thus avoiding exposure to the leaching action of liquid fixatives. After resin infiltration, the cellular distribution of fluorine was determined in ultrathin sections with a Zeiss CEM902 electron microscope equipped for electron energy loss spectroscopy.

RESULTS

Fluorine was detected primarily in association with intracellular membranes, particularly membranes of the endoplasmic reticulum (p < 0.05 at 20 minutes by morphometric analysis). Fluorine also was detected in association with membranes of the Golgi apparatus. The fluorine signal was confirmed by serial spectra of cell regions containing these organelles (p < 0.01), but was not detectable in the free cytosol, mitochondria or extracellular medium, nor in hepatocytes not exposed to C-FBAL.

CONCLUSIONS

We conclude that cryofixation and freeze-dry processing followed by electron microscopy with electron energy loss spectroscopy is a valuable technique for examining intracellular processing of bile salts. Our results suggest that bile salts localize to the membranes, but not lumena, of organelles during hepatocyte exposure to bile salts, calling into question the proposed role for vesicular transport of bile salts within hepatocytes.

Contribution of osmium tetroxide to the image quality and detectability of iron in cells studied by electron spectroscopic imaging and electron energy loss spectroscopy

The detection of elemental distributions within ultrastructural cellular components presents a number of challenges. There are many technical questions that need to be resolved including optimal fixation protocols. Another is the impact of heavy metals, such as osmium tetroxide (OsO4), on the detectability of other elements when OsO4 is used in chemical fixation protocols for biological samples. OsO4 was examined by varying its concentrations from 0% to 1% and time of fixation from 5 to 30 minutes with hamster alveolar macrophages. The morphological quality of cellular images observed and the detectability of iron using electron spectroscopic imaging (ESI) and electron energy loss spectroscopy (EELS) were evaluated. One percent OsO4 for 30 minutes in the chemical fixation protocol enhances the quality of the ESI and does not interfere with the ESI or EELS signal of iron. Positive results from both methods indicate the presence of the specific element. The loss of 59Fe during the chemical fixation procedure was also studied. Less than 10% was lost during the primary fixation step, but minimal losses occurred through dehydration, embedding, and sectioning. Careful technical assessment of the presence of an element as well as factors which might interfere with its detection is an important step in the application of any analytical microscopic technique.

Responses of human neutrophils to sulfite

Exposure to sulfur dioxide or sulfite aerosols induce inflammatory reactions in the respiratory tract characterized by an influx of neutrophils into the airways. To determine direct intracellular effects of sulfite on human neutrophils, these cells were evaluated ultrastructurally by electron microscopy and analyzed for their extracellular and intracellular respiratory burst activity after incubation with sulfite (0.01-10 mM) in vitro. The respiratory burst was quantitated by measuring both the extracellular release of superoxide anions (O2-) by superoxide dismutase-inhibitable lucigenin-dependent chemiluminescence (CL) and the intracellular generation of hydrogen peroxide (H2O2) by flow cytometry using the reagent dichlorofluorescein diacetate. The addition of sulfite in concentrations of 0.01-1 mM resulted in sixfold increases in CL of resting neutrophils. Neutrophils stimulated with zymosan, phorbol myristate acetate (PMA), or N-formyl-methionine-leucine-phenylalanine further increased CL when sulfite was added. Higher sulfite concentrations (2-10 mM) decreased CL of resting, zymosan-stimulated, and PMA-stimulated cells. When sulfate was added, no changes in CL of resting and zymosan-stimulated neutrophils were seen, indicating that the effect is specific for sulfite. The intracellular generation of H2O2 in resting and PMA-stimulated neutrophils incubated with sulfite (0.1-2 mM) was increased twofold. These findings suggest that sulfite in low concentrations stimulates neutrophils by activating the respiratory burst to produce O2- and H2O2. Ultrastructural studies confirm the stimulating effect of sulfite on neutrophils with sulfite-treated cells exhibiting increased ruffled surface membranes, degranulation changes, and vesiculation similar to those seen in PMA-stimulated cells.

Particle opsonization and lung macrophage cytokine response. In vitro and in vivo analysis

Inhaled inert particles and organisms cause a spectrum of pulmonary responses, ranging from minimal changes to marked acute inflammation. During ingestion and clearance of such particles, alveolar macrophages (AM) can initiate pulmonary inflammation by production of TNF and neutrophil chemoattractant cytokines. We tested the role of opsonization in determining the AM response to ingestion of inert particles in vitro and in vivo. As measures of AM activation after phagocytosis in vitro, we measured release of TNF and mRNA expression for the platelet-factor 4 family neutrophil chemoattractants, KC and macrophage-inflammatory protein-2 (MIP-2). Using albumin-coated fluorescent latex particle as phagocytic targets, we found a marked release of TNF by AM ingesting particles opsonized with antialbumin IgG, although uptake of similar numbers of unopsonized particles caused little or no release (e.g., 4648 +/- 1147 pg/ml, opsonized beads vs 576 +/- 205 unopsonized, 10:1 particle:cell ratio, n = 4, mean +/- SD). Flow cytometry confirmed equal uptake of the two particle types. Northern analysis of AM mRNA showed marked induction of KC and MIP-2 mRNA after ingestion of opsonized particles only. Instillation of opsonized particles into hamster lungs caused a marked neutrophil influx, although unopsonized particles did not. TNF was elevated in lavage fluid after instillation of opsonized particles, but not after unopsonized beads (92.7 +/- 136 pg/ml opsonized, n = 7 vs 1.3 +/- 3.6 unopsonized, n = 6). KC and MIP-2 mRNA were induced in lavaged cells after instillation of opsonized but not after unopsonized particles or vehicle control. The nature of particle interaction with the AM surface during phagocytosis determines the subsequent AM response. Although many unopsonized inert particles are ingested with minimal AM activation, specific opsonization of pathogens or non-specific adsorption of Ig onto other particles may activate AM and lead to pulmonary inflammation.

Particle opsonization and lung macrophage cytokine response. In vitro and in vivo analysis

Inhaled inert particles and organisms cause a spectrum of pulmonary responses, ranging from minimal changes to marked acute inflammation. During ingestion and clearance of such particles, alveolar macrophages (AM) can initiate pulmonary inflammation by production of TNF and neutrophil chemoattractant cytokines. We tested the role of opsonization in determining the AM response to ingestion of inert particles in vitro and in vivo. As measures of AM activation after phagocytosis in vitro, we measured release of TNF and mRNA expression for the platelet-factor 4 family neutrophil chemoattractants, KC and macrophage-inflammatory protein-2 (MIP-2). Using albumin-coated fluorescent latex particle as phagocytic targets, we found a marked release of TNF by AM ingesting particles opsonized with antialbumin IgG, although uptake of similar numbers of unopsonized particles caused little or no release (e.g., 4648 +/- 1147 pg/ml, opsonized beads vs 576 +/- 205 unopsonized, 10:1 particle:cell ratio, n = 4, mean +/- SD). Flow cytometry confirmed equal uptake of the two particle types. Northern analysis of AM mRNA showed marked induction of KC and MIP-2 mRNA after ingestion of opsonized particles only. Instillation of opsonized particles into hamster lungs caused a marked neutrophil influx, although unopsonized particles did not. TNF was elevated in lavage fluid after instillation of opsonized particles, but not after unopsonized beads (92.7 +/- 136 pg/ml opsonized, n = 7 vs 1.3 +/- 3.6 unopsonized, n = 6). KC and MIP-2 mRNA were induced in lavaged cells after instillation of opsonized but not after unopsonized particles or vehicle control. The nature of particle interaction with the AM surface during phagocytosis determines the subsequent AM response. Although many unopsonized inert particles are ingested with minimal AM activation, specific opsonization of pathogens or non-specific adsorption of Ig onto other particles may activate AM and lead to pulmonary inflammation.

Sulfite stimulates NADPH oxidase of human neutrophils to produce active oxygen radicals via protein kinase C and Ca2+/calmodulin pathways

The effect of sulfite on the oxidative metabolism of human neutrophils was studied in vitro. Superoxide anion production of PMN was determined using superoxide dismutase-inhibitable lucigenin-dependent CL. The addition of sulfite in concentrations of 0.01 mM-1 mM results in an up to 6-fold increase in CL of nonstimulated neutrophils at 37 degrees C and pH 7. Neutrophils stimulated with zymosan or PMA have an additional 2-fold stimulation when sulfite is added. Higher sulfite concentrations (2 mM-10 mM) decrease the CL of both nonstimulated and stimulated cells. The activity of NADPH oxidase, responsible for O2.- production, is significantly increased in neutrophils incubated with 1 mM sulfite. Neutrophils from patients with chronic granulomatous disease, which are cytochrome b558 negative or have p47phox deficiency, exhibit no significant NADPH oxidase activity and show no increase in CL by sulfite. Inhibitors of protein kinase C, H7, and calphostin C, as well as inhibitors of Ca(2+)- and calmodulin-dependent processes, W7, and R 24 571, completely inhibited the increased CL of sulfite-treated neutrophils. These findings indicate that sulfite in low concentrations stimulates neutrophils to produce superoxide anions by activation of NADPH oxidase through a signal transduction pathway involving protein kinase C and Ca2+/calmodulin.

Relationship among mediators, inflammation, and volume history with antigen versus hyperpnea challenge in guinea pigs

Paralyzed mechanically ventilated guinea pigs constricted to a similar degree by either isocapnic hyperpnea or antigen challenge display significantly different lung resistance (RL) volume history responses to a deep breath. We compared bronchoalveolar lavage (BAL) mediator profiles, BAL total protein concentrations, and tissue histopathology of antigen-constricted (AC), hyperpnea-constricted (HC), and control guinea pigs to determine whether patterns of volume history near peak constriction could be related to specific patterns of lung mediators, indices of microvascular leakage, or severity of tissue inflammation assessed pathologically. Methacholine constricted (MC) animals served as a second control group for assessing the effects of direct smooth-muscle contraction on indices of inflammation and volume history responses. Our results show that despite similar baseline and postchallenge RL, HC and MC animals displayed significant constriction reversal after a deep lung inflation, whereas AC animals did not. BAL concentrations of prostaglandin D2(PGD2), thromboxane B2 (TxB2), and leukotriene C4/D4/E4 (slow reacting substance of anaphylaxis, SRSA) were significantly elevated in both AC and HC animals compared with control and MC animals, with AC and HC BAL differing only with respect to PGD2 values (AC 2.4-fold higher). BAL total protein in AC animals was significantly greater than in HC, MC, and control animals. Histopathology showed significant peribronchial and interstitial cellular inflammation in AC animal specimens, whereas specimens from HC animals had little or no inflammation. Differences in volume history responses observed between equally constricted AC, HC, and MC animals may be due to differences in airway and/or parenchymal microvascular leak and cellular inflammation.

Expression of macrophage inflammatory protein-2 and KC mRNA in pulmonary inflammation

This study sought to test the hypothesis that expression of mRNA for two cytokines, macrophage inflammatory protein-2 (MIP-2) and the KC gene product, is induced in rat lung cells during inflammatory responses in vitro and in vivo. Macrophage inflammatory protein-2 and KC are members of the platelet-factor 4 (PF-4) cytokine superfamily that cause marked neutrophil chemotaxis and activation in vitro. To investigate expression of the genes for MIP-2 and KC in rat models of lung injury, cDNA probes for these cytokines in the rat were made from polymerase chain reaction (PCR) products generated using mouse sequence-derived primers. Sequence analysis of these cDNAs showed marked homology to known murine sequences (89% and 92% MIP-2 and KC, respectively). These cDNAs were first used to study the expression of these two genes in rat alveolar macrophages (AMs) in vitro by Northern blot hybridization. Lipopolysaccharide (LPS) treatment of rat AMs in vitro caused marked increases in mRNA for both KC and MIP-2 within 30 minutes, which persisted through the 6 hours measured. To study expression during inflammation in vivo, rats were treated with LPS by intratracheal instillation. Bronchoalveolar lavage (BAL) cells and whole trachea homogenates were analyzed. There was a marked and rapid increase in MIP-2 and KC mRNA levels within both BAL cells and trachea homogenates after LPS instillation. The results support the hypothesis that MIP-2 and KC cytokines contribute to neutrophil chemotaxis and activation in this rat model of acute pulmonary inflammation.

Toxicity of intratracheally instilled cotton dust, cellulose, and endotoxin

Cotton dust includes respirable particles containing endotoxin and elastase, agents associated with emphysema. To examine whether a respirable fraction of cotton dust could produce emphysema in an animal model, we intratracheally instilled hamsters with respirable cotton dust particles (0.75 mg/100-g animal), mass median aerodynamic diameter less than or equal to 4.8 microns, twice weekly for 6 wk. We also examined whether instilled endotoxin (255 micrograms/100-g animal) could produce emphysema in hamsters and whether cellulose (0.75 mg/100-g animal) is an appropriate inert comparison dust. A saline-instilled group was the control. Hamsters were killed 8 wk after the last instillation. Static pressure-volume deflation curves of air-filled excised lungs were analyzed to measure lung distensibility. Lungs were fixed in inflation using glutaraldehyde and were examined morphometrically to obtain surface area and numbers of granulomata. Endotoxin-treated animals had increased distensibility, reduced surface-to-volume (S/V) ratio, and morphologically apparent mild centrilobular emphysema. Cellulose-treated animals had decreased distensibility, normal S/V ratio, and significant numbers of granulomata with patchy areas of thickened interalveolar septa. Cotton-dust-instilled animals had normal distensibility, reduced S/V ratio, significant numbers of granulomata, and mild centrilobular emphysema. These data suggest that cotton dust produces a significant parenchymal lesion with elements similar to both the emphysematous response to endotoxin and the fibrotic nodular response to cellulose.

Selective down-regulation of alveolar macrophage oxidative response to opsonin-independent phagocytosis

We have compared the oxidative response of alveolar macrophages (AM) during opsonin-dependent and independent phagocytosis by using multiparameter flow cytometry. The respiratory burst of AM during phagocytosis was quantitated by the intracellular oxidation of the nonfluorescent precursors dichlorofluorescin diacetate (DCFH) or hydroethidine (HE, a reduced precursor of ethidium) to their fluorescent (oxidized) counterparts. After loading freshly isolated normal hamster AM with DCFH or HE, red or green fluorescent beads, respectively, were added to the shaking cell suspensions. Ingestion of opsonized particles by AM caused a marked increase in oxidation of both DCFH and HE proportional to the number of beads ingested. In contrast, uptake of one to three unopsonized particles per cell led to inhibition of oxidative activity compared to control cells incubated without particles. AM ingesting four or more unopsonized particles showed some increase in oxidative metabolism, but far less than that with identical numbers of particles in opsonin-dependent ingestion. Similar results were obtained using fluorescent labeled staphylococcal bacteria. Using three-color flow cytometry to study cells ingesting both types of particles, cells first ingesting unopsonized beads were also found to have an inhibited oxidative response to subsequently ingested opsonized particles. The mitochondrial poison antimycin inhibited most of the intracellular oxidative response to either type of phagocytosis. The remaining antimycin-insensitive, membrane derived respiratory burst of AM was also substantially diminished after phagocytosis of unopsonized particles vs similar numbers of opsonized particles. The greatly increased mitochondrial respiration in AM during phagocytosis of opsonized particles may be related to bactericidal mechanisms. Killing of ingested Staphylococcus by AM was markedly impaired in the presence of antimycin. The results suggest that AM may ingest the numerous, unopsonized inert particles that are inhaled without generation of potentially toxic oxygen metabolites, while retaining the capacity to undergo a respiratory burst after ingesting opsonized particles and bacteria. The mechanism(s) for this distinct response may include generation of an inhibitor of intracellular oxidative metabolism.

Selective down-regulation of alveolar macrophage oxidative response to opsonin-independent phagocytosis

We have compared the oxidative response of alveolar macrophages (AM) during opsonin-dependent and independent phagocytosis by using multiparameter flow cytometry. The respiratory burst of AM during phagocytosis was quantitated by the intracellular oxidation of the nonfluorescent precursors dichlorofluorescin diacetate (DCFH) or hydroethidine (HE, a reduced precursor of ethidium) to their fluorescent (oxidized) counterparts. After loading freshly isolated normal hamster AM with DCFH or HE, red or green fluorescent beads, respectively, were added to the shaking cell suspensions. Ingestion of opsonized particles by AM caused a marked increase in oxidation of both DCFH and HE proportional to the number of beads ingested. In contrast, uptake of one to three unopsonized particles per cell led to inhibition of oxidative activity compared to control cells incubated without particles. AM ingesting four or more unopsonized particles showed some increase in oxidative metabolism, but far less than that with identical numbers of particles in opsonin-dependent ingestion. Similar results were obtained using fluorescent labeled staphylococcal bacteria. Using three-color flow cytometry to study cells ingesting both types of particles, cells first ingesting unopsonized beads were also found to have an inhibited oxidative response to subsequently ingested opsonized particles. The mitochondrial poison antimycin inhibited most of the intracellular oxidative response to either type of phagocytosis. The remaining antimycin-insensitive, membrane derived respiratory burst of AM was also substantially diminished after phagocytosis of unopsonized particles vs similar numbers of opsonized particles. The greatly increased mitochondrial respiration in AM during phagocytosis of opsonized particles may be related to bactericidal mechanisms. Killing of ingested Staphylococcus by AM was markedly impaired in the presence of antimycin. The results suggest that AM may ingest the numerous, unopsonized inert particles that are inhaled without generation of potentially toxic oxygen metabolites, while retaining the capacity to undergo a respiratory burst after ingesting opsonized particles and bacteria. The mechanism(s) for this distinct response may include generation of an inhibitor of intracellular oxidative metabolism.

In vitro dissolution of uniform cobalt oxide particles by human and canine alveolar macrophages

Intracellular dissolution of inhaled particles is an important pathway of clearance of potentially toxic materials. To study this process, monolayers of human and canine alveolar macrophages (AM) were maintained alive and functional in vitro for more than 2 wk. Complete phagocytosis of moderately soluble, monodisperse 57Co3O4 test particles of four different sizes was obtained by optimizing the cell density of the monolayer and the particle-to-cell ratio. The fraction of the initial particle mass that was soluble increased over time when the particles were ingested by AM but remained constant when in culture medium alone. Smaller particle sizes had a faster characteristic intracellular dissolution rate constant than did larger particles. The dissolution rates differed between AM obtained from two human volunteers as compared to those obtained from six mongrel dogs. These in vitro dissolution rates were very similar to in vivo translocation rates previously obtained from human and canine lung clearance studies after inhalation of the same or similar monodisperse, homogeneous 57Co3O4 test particles. We believe an important clearance mechanism for inhaled aerosol particles deposited in the lungs can be simulated in vitro in a cell culture system.

Oxidative metabolism in the alveolar macrophage: analysis by flow cytometry

We evaluated the reagents dichlorofluorescin (DCFH) and hydroethidine (HE) for use in flow cytometric analysis of the respiratory burst of alveolar macrophages and monocytes. DCFH and HE are non-fluorescent precursors which can be oxidized intracellularly to the fluorescent compounds dichlorofluorescein and ethidium. Alveolar macrophages (AMs) loaded with either DCFH or HE were analyzed after phorbol myristate acetate (PMA) stimulation. The results, expressed as fmol/cell oxidation product (DCF or ethidium) after fluorometric standardization of the flow cytometer, show that both DCFH (273 +/- 48, mean increase over control +/- SE, fmol/cell, N = 9) and HE (416 +/- 54, N = 11) detected the substantial respiratory burst of hamster AMs. Similar results were obtained with normal human AMs. By using multiparameter analyses, the oxidative response of AMs ingesting opsonized fluorescent latex beads was measured in subpopulations ingesting increasing numbers of particles. A graded increase in oxidation of both DCFH and HE was found in response to increasing phagocytosis. Ingestion of fluoresceinated staphylyococcal bacteria caused similar changes in HE-loaded AMs. Inhibition of respiration with antimycin showed that approximately 95% of the increased oxidative metabolism of hamster AMs ingesting opsonized beads or bacteria was mitochondrial. The remaining 5% (10-40 fmol/cell) is membrane-derived oxidative activity quantitatively similar to that measured in assays of extracellular release of H2O2. Monocytes loaded with either DCFH or HE showed substantial increases in fluorescence after PMA stimulation (mean % increase over control +/- SE at 30 min: 464 +/- 104, DCFH, 505 +/- 156, HE). While DCHF is known to measure H2O2, HE is less well characterized. Exposure of cells to an extracellular source of both superoxide anion (O2-) and H2O2, xanthine oxidase-xanthine, resulted in marked oxidation of intracellular HE. Addition of both superoxide dismutase and catalase blocked this oxidation, indicating that HE can detect both O2- and H2O2. These agents can be useful probes for precise analysis of oxidative metabolism during phagocytosis in AMs and other mononuclear phagocytes.

Development of surface membrane characteristics of "premedullary" macrophages in organ cultures of embryonic rat and hamster lungs

A replicating population of non-monocyte-derived free cells appears in organ-cultured embryonic rat lungs, indistinguishable from alveolar macrophages by classical criteria such as ultrastructure, lysosomal enzyme cytochemistry, and phagocytic behavior. We demonstrate similar events in cultured embryonic hamster lungs and development of macrophage-associated properties on the plasmalemma of these cells in both species. Immunoperoxidase localizations were obtained using monoclonal antibodies against alveolar macrophage antigen (HAM1) in hamsters, and rat macrophage antigen (ED1) and leukocyte-common antigen (OX1) in rats. Fc and C3b receptors were identified in both species by immune rosetting. HAM1 staining, perinuclear in rare cells at explantation, gains definitive surface localization 3-4 days later as cells prepare to emerge through the pleura. ED1 and OX1 cytoplasmic staining first occurs after 24 hr, increases as macrophages multiply and congregate beneath the pleura, and translocates to the plasmalemma of emerged cells. Some glass-adherent cells from lung explants have Fc receptors. The proportion rises sharply for 24 hr and equals fully emerged cells (90-95%) by days 3-4. At first phagocytosis is slow to follow Fc receptor binding, but ingestion time decreases to 3-10 min as macrophages mature. A minority of emerged macrophages bind complement-opsonized erythrocytes, which are rarely taken up. These properties are shared by alveolar macrophages of adults.

Isolation and antigenic identification of hamster lung interstitial macrophages

Lung interstitial macrophages (IMs) are a large, distinctive population of cells with important proliferative capacities. Characterization of their role in health and disease has been hampered by inadequate methods to separate interstitial from residual alveolar macrophages (AMs) in preparations of individual mononuclear cells from lung tissue. In this study, a specific cell-surface antigen (HAM1) present on more than 90% of hamster AMs, but not expressed by hamster IMs, was used to distinguish these populations. After collagenase digestion of lung tissue slices from exhaustively lavaged and perfused hamster lungs, mononuclear phagocytes were isolated by density gradient centrifugation. The mean yield of lung digest macrophages (3.9 +/- 1.9 (SD) x 10(6] was comparable to the yield of lavaged AMs (4.2 +/- 1.9 x 10(6]. The proliferative capacity of lavaged AMs, blood monocytes, and lung digest macrophages was compared using a soft-agar colony-forming unit (CFU) assay. Both lung digest macrophages and blood monocytes had significantly more CFUs (68.7 +/- 2.6 and 53.5 +/- 8.4 CFU/10(3) cells [mean +/- SEM], respectively) than did AMs (16.5 +/- 1.7) (p less than 0.01). To further define the composition of the lung digest macrophage population, flow cytometric analysis of fixed cells from six experiments was performed using a mouse monoclonal antibody specific for the HAM1 antigen found only on AMs. The lung digest macrophage population consisted of both antigen-negative IMs (78.2% +/- 3.7% [SEM]; n = 6) and antigen-positive, residual AMs (21.8% +/- 3.7%). Morphometric counts confirmed that substantial numbers of AMs are left behind after lavage and contribute to macrophages obtained from lung tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical suspicion of autopsy-proven thrombotic and tumor pulmonary embolism in cancer patients

Cancer patients are prone to both thrombotic and tumor pulmonary embolism (PE). To identify similarities and differences in their clinical features, we reviewed all autopsies from 1978 to 1982 at Brigham and Women's Hospital and the Dana Farber Cancer Institute. Of 73 patients with solid malignant tumors and PE, 56 had major thrombotic PE and 17 had major tumor embolism to the lungs. Of the 56 with cancer and thrombotic PE, 25 (45%) had the correct diagnosis suspected antemortem. By contrast, only 1 of 17 (6%) patients with tumor embolism was diagnosed correctly antemortem (p = 0.005). Most presenting symptoms, signs, laboratory values, and associated conditions were not markedly different in patients with thrombotic PE and tumor embolism. These findings indicate that tumor PE is more difficult to diagnose clinically and may be misdiagnosed as thrombotic PE. Finally, these data suggest that in all cancer patients, the presence of both thrombotic and tumor PE should be considered because of similarities in their clinical features.

Cavitary lung nodules associated with combination chemotherapy containing bleomycin

We describe a patient in whom multiple cavitary lung nodules developed without infectious symptoms after treatment with bleomycin, cisplatin and vinblastine combination chemotherapy for metastatic testis cancer. Open lung biopsy demonstrated extensive granuloma formation without evidence of malignancy or infection. This report extends the spectrum of bleomycin pulmonary toxicity to include cavitary pulmonary nodules associated with granuloma formation.

Emphysema alters the deposition pattern of inhaled particles in hamsters

How does pulmonary emphysema affect aerosol deposition? Groups of awake hamsters with emphysema (intratracheal elastase, 0.2 mg/100 g body wt) and age-matched controls (intratracheal saline) were exposed for 30 minutes to an insoluble radioactive aerosol (0.45 mu aerodynamic diameter) at 30, 60, or 90 days after instillation. Immediately after exposure, the animals were sacrificed. The lungs were excised, dried at total lung capacity, and sliced into 1-mm thick sections. Each slice was cut into pieces, which were counted for radioactivity and weighed. Then a measure of the uniformity of deposition, the evenness index (EI), was calculated. With perfect uniformity, all EIs would be one. We found fewer particles in the emphysematous, as compared with the control, lungs at 60 or 90 days after elastase instillation. The deposited particles were distributed less uniformly throughout the emphysematous lungs than in the control lungs. In controls, the standard deviation (SD) of the EI distribution (mean 1.0) averaged 0.33 for the three times studied. In elastase animals, the SD increased to 0.48 at 30 days, and at 60 days and 90 days the distributions were no longer normally distributed. This increased heterogeneity of deposition was also manifested as a loss of the normal apex-base gradient observed in control animals, an increase in the amount of nonventilated parenchyma, enhanced airway deposition, and an altered lobar deposition pattern. Morphometric analysis showed an increase in the mean linear intercept (MLI) of emphysematous lungs as compared with control lungs. However, the author found no correlation between MLI, a measure of emphysema, and EI, a measure of deposition, quantified in the same lung pieces. It is concluded that the emphysematous lesions produced by elastase markedly alter the deposition of an inhaled submicrometric aerosol. Factors that may contribute to these changes include airway obstruction and differences in breathing pattern in emphysematous as compared with control animals.

Detection of lymphokines and lymphokine receptors in pulmonary sarcoidosis. Immunohistologic evidence that inflammatory macrophages express IL-2 receptors

In an investigation of the immunopathogenesis of sarcoidosis, the authors undertook the tissue localization of those lymphokines and lymphokine receptors which are known to play a central role in T-cell and macrophage activation. Using monoclonal antibodies and an ABC immunoperoxidase technique. They determined the distribution of gamma interferon (IFN-g), interleukin-2 (IL-2), and corresponding IL-2 receptors (IL-2R), plus T cells and T cell subsets, B cells, and macrophages within thoracic lymph nodes and lung specimens of 9 patients with active pulmonary sarcoidosis. Epithelioid and multinucleate giant cells within sarcoid granulomas of all specimens showed membrane labeling for IL-2R and IFN-g, in addition to IL-2, suggesting that these cells indeed express functional IL-2 receptors. Infiltrating T cells, largely T4+, were also IL-2R+, and many showed IL-2 and IFN-g labeling. By comparison, macrophages within sections of normal lung or lymph node failed to stain for IL-2, IL-2R, or IFN-g. These immunohistologic studies extend recent in vitro observations by these authors and others that normal human blood monocytes and alveolar macrophages are induced by IFN-g or IL-2 to express functional membrane-bound IL-2 receptors. The in vivo expression of IL-2R by mononuclear phagocytes in pulmonary sarcoidosis is demonstrated, and a new role is suggested for T-cell-derived lymphokines in macrophage activation.

Inhibition of immune opsonin-independent phagocytosis by antibody to a pulmonary macrophage cell surface antigen

Unlike other hamster phagocytes, hamster pulmonary macrophages (PM) avidly ingest albumin-coated latex particles in the absence of serum. They also possess a highly specific cell surface antigen. To evaluate the relationship between these two characteristics, PM were incubated with mouse monoclonal antibody directed against the PM antigen. After unbound antibody was removed, the amount of bound antibody and the phagocytic capability of PM were measured by flow cytometry and fluorescence microscopy. Maximum antibody binding produced a 25% inhibition of ingestion. Particle attachment was not affected. This effect was antigen specific, since neither a nonspecific mouse myeloma protein of the same subclass nor a mouse antibody that bound to another hamster surface antigen had any effect on binding or ingestion. If antigen-specific F(ab')2 fragments were introduced both before and during the period of phagocytosis, the inhibition of particle ingestion approached 100%. Particle binding increased at low F(ab')2 concentrations but declined at higher concentrations. Because calcium may play a role in the ingestion process, the effect of antibody on 45Ca uptake was evaluated. It was observed that antigen-specific F(ab')2 fragments stimulated 45Ca uptake, whereas control antibodies did not. These results suggest that the antigen reacting with our anti-hamster PM monoclonal antibody is involved in immune opsonin-independent phagocytosis and that calcium participates in this phagocytic process.

Inhibition of immune opsonin-independent phagocytosis by antibody to a pulmonary macrophage cell surface antigen

Unlike other hamster phagocytes, hamster pulmonary macrophages (PM) avidly ingest albumin-coated latex particles in the absence of serum. They also possess a highly specific cell surface antigen. To evaluate the relationship between these two characteristics, PM were incubated with mouse monoclonal antibody directed against the PM antigen. After unbound antibody was removed, the amount of bound antibody and the phagocytic capability of PM were measured by flow cytometry and fluorescence microscopy. Maximum antibody binding produced a 25% inhibition of ingestion. Particle attachment was not affected. This effect was antigen specific, since neither a nonspecific mouse myeloma protein of the same subclass nor a mouse antibody that bound to another hamster surface antigen had any effect on binding or ingestion. If antigen-specific F(ab')2 fragments were introduced both before and during the period of phagocytosis, the inhibition of particle ingestion approached 100%. Particle binding increased at low F(ab')2 concentrations but declined at higher concentrations. Because calcium may play a role in the ingestion process, the effect of antibody on 45Ca uptake was evaluated. It was observed that antigen-specific F(ab')2 fragments stimulated 45Ca uptake, whereas control antibodies did not. These results suggest that the antigen reacting with our anti-hamster PM monoclonal antibody is involved in immune opsonin-independent phagocytosis and that calcium participates in this phagocytic process.

Immunohistologic analysis of a human pulmonary alveolar macrophage antigen

PAM1 is a 200-kDa polypeptide antigen present on lavaged human alveolar macrophages but not on monocytes, peritoneal macrophages, breast milk macrophages, or other normal hematopoietic cells studied by flow cytometry. We have characterized the distribution of expression of this antigen by cells in tissues by using immunohistologic techniques. Normal and diseased lung as well as lymph nodes, spleen, kidney, liver, GI tract, and skin were studied. PAM1 was expressed strongly on the surface and weakly in the cytoplasm of most alveolar macrophages in all 15 of the lung specimens. Occasional interstitial macrophages had weak to moderate staining for this antigen but the majority did not stain. The distribution, pattern, and intensity of staining for PAM1 was the same in normal lung specimens and those with interstitial pneumonitis, despite the increase in mononuclear cells in the latter. Dermal histiocytes and Kuppfer cells expressed PAM1 weakly. Sinus histiocytes in lymph nodes were moderately to strongly positive. Although lymphoid cell suspensions (tonsil) were negative by flow cytometry, five of six lymph nodes had positive cells by immunohistology. PAM1 was also detected on endothelial cells of splenic sinusoids in all 6 specimens but not on any other endothelium. Hence, while PAM1 is expressed most strongly on alveolar macrophages, it can also be demonstrated in other locations using sensitive immunohistologic techniques. Since circulating monocytes are antigen negative and some lung interstitial macrophages bear antigen, PAM1 may be a useful marker for studies of the differentiation of mononuclear cells in the lung.

Ultrastructural analysis of a specific hamster alveolar macrophage antigen

Alveolar macrophages of hamsters have a cell surface antigen not found on other pulmonary cells or macrophages from other sites. A specific mouse monoclonal antibody and protein A-colloidal gold were used to study the distribution of this antigen at the ultrastructural level. By quantitating the number of antigenic sites per unit linear distance of membrane of the total cell surface, it was established that this antigen is randomly distributed on the plasma membrane. Cell-to-cell heterogeneity in antigen density was correlated with other ultrastructural features of lung macrophages studied morphometrically. A strong correlation (r = 0.77) between antigen density and secondary lysosome content was found, supporting the thesis that expression of this antigen increases with macrophage age. No apparent topographic relationship of surface antigen to any cytoplasmic organelles could be inferred from the ultrastructural morphology. This study also used immuno-ultrastructural techniques to visualize stages of the internalization of labeled antigen in live cells. While some cells retained a random distribution of antigen at 0 degrees C, most showed movement of antigenic sites away from pseudopodia to clusters on more linear (less ruffled) portions of cell surface. At 37 degrees C, the antigen was internalized and could be visualized within coated pits and endocytic vacuoles. Definition of the anatomic distribution of this antigen under various conditions provides a baseline for further ultrastructural investigations of the function of this antigen.

Short-term regional clearance of an inhaled submicrometric aerosol in pulmonary fibrosis

Regional clearance of submicrometric aerosol during 5 days was studied in control hamsters and in those with diffuse interstitial pulmonary fibrosis. Fibrosis was induced by treatment with bleomycin (1.6 U/kg) and oxygen (70% for 72 h) 80 days earlier. Diseased and control animals were exposed for 30 min to an insoluble colloidal 198Au aerosol (AMAD, 0.62 micron; sigma g, 1.35). Five diseased and 6 control animals were killed immediately (Day 0); 6 diseased and 6 control animals were killed 5 days later (Day 5). All lungs were excised, dried at TLC, sliced into 1-mm sections, and dissected into pieces. When compared with deposition in Day 0 control lungs, 26.3% of the particles had been cleared 5 days after exposure from the control lungs. Diseased animals cleared 44.6% of the particles (p less than 0.05, compared with Day 0 diseased animals). Examination of regional clearance on the basis of lobar differences, apex to base levels, and presence of airways also reflected increased clearance in the fibrotic animals. The parenchymal distribution of particle retention at Day 0 was less uniform in the fibrotic animals than in the control animals and was not significantly altered after 5 days of clearance in either group. Particle clearance may be greater in diseased lungs because of accelerated alveolar-bronchiolar transport of particles or particle-containing macrophages.