Effects of asbestos on initiation of DNA damage, induction of DNA-strand breaks, P53-expression and apoptosis in primary, SV40-transformed and malignant human mesothelial cells

Human mesothelial cells (HMC), the progenitor cells of asbestos-induced mesothelioma, are particularly sensitive to the genotoxic effects of asbestos, although the molecular mechanisms by which asbestos induces injury in HMC are not well known. The high susceptibility of HMC to simian virus 40 (SV40)-mediated transformation is assumed to play a causative role in the pathogenesis of mesothelioma. The aim of this study was to investigate the asbestos-induced DNA damage in cultured HMC and SV40-transformed HMC (MeT-5A) compared with their malignant counterparts, i.e. human mesothelioma cells (MSTO). The time-dependent initiation of DNA-strand breaks as well as the induction of oxidative DNA base modifications were key factors for investigation. HMC, MeT-5A and MSTO cells were exposed to chrysotile and crocidolite asbestos (3 microg/cm2) during different time periods (1-72 h). DNA damage was investigated by use of the Comet assay and alkaline unwinding, the latter in combination with the Fpg protein. The P53 level was analyzed by immunofluorescence, and measurement of apoptosis was conducted by flow cytometry. We found a significant induction of DNA damage in asbestos-treated HMC already after an exposure time of 1.5 h. This effect could not be observed in treated MeT-5A and MSTO cells. Also, a time-dependent significant increase in DNA-strand breaks was observed by alkaline unwinding in asbestos-treated HMC, but not in treated MeT-5A and MSTO cells. In none of the three cell lines we could detect oxidative DNA damage recognized by the Fpg protein (e.g. 8-oxo-guanine), up to 24 h after exposure to asbestos. In contrast to what was found in HMC, P53 was over-expressed in untreated MeT-5A and MSTO. The induction of apoptosis by asbestos fibers was suppressed in MeT-5A and MSTO cells. Crocidolite fibers induced the higher genotoxic effects and chrysotile the more pronounced apoptotic effects. We conclude that asbestos induces DNA damage in HMC already after a very short exposure time in the absence of 8-oxo-guanine formation. The presence of SV40-Tag in MeT-5A and MSTO cells results in an increased expression of P53, but not in additive genotoxic effects after exposure to asbestos. The deregulation of the apoptotic pathway may lead to proliferation of genomically damaged cells and finally to the development of mesothelioma.

Induction of mitotic cell division distrubances and mitotic arrest by pyrethroids in V79 cell cultures

Five pyrethroids (fenvalerate, deltamethrin, cypermethrin, permethrin, cyfluthrin) differing in their chemical purity were investigated on their cytotoxic effects, especially on their ability to induce mitotic cell division disturbances using Chinese hamster lung cells of line V79. The colony forming ability (CFA) resulted in distinct differences of the cytotoxic effect of the tested pyrethroids, whereby permethrin was found to be most toxic. With the exception of fenvalerate all tested pyrethroids gave rise to inhibition of cell cycle progression as shown by G2/M-arrest of synchronized V79 cells by flow cytometry as well as by the increase of the mitotic index as evaluated by light microscopy. The mitotic arresting activity could be attributed to the occurrence of abnormal mitotic figures such as initial and full C-metaphases. The results however indicate, that pyrethroids per se do not contribute to the cytotoxic effects but that other factors such as chemical impurities, source as well as manufacturing process and isomer composition may be responsible for the observed cytotoxic effects.

Malignant transformation of Syrian hamster kidney cells in vitro by interaction of airborne particulates and simian virus (SV-) 40

Permanent inhalation of great variety of air pollutants raises serious problems concerning adverse effects on human health. Especially in airborne particulates more than 1000 inorganic and organic compounds have been detected, among them also carcinogens and mutagens, such as polycyclic aromatic hydrocarbons, polycyclic-aza-compounds, carbonic acids, phenols, ketons, heavy metals, etc. The role of airborne particulates in genesis of the most common cancer in man, the bronchogenic carcinoma, is still unresolved. Samples of airborne particulates were collected at locations of the highly industrialized Rhine-Ruhr region (Germany) employing a high volume sampler HVS-150 (Ströhlein Instruments) prepared with glass fibre filters. Samples were extracted in a Soxhlet-apparatus with dichloromethane. Using a rotating evaporator the solvent was evaporated and the residual substances dissolved in dimethylsulfoxide for cell culture experiments. Carcinogenic activity of extracts of airborne particulates was evaluated by the bioassay of 'enhancement' of malignant cell transformation in vitro. In this bioassay, exponentially growing cell cultures from kidneys of the Syrian golden hamster were treated with various concentrations of extracts of airborne particulates for 18 h. Thereafter, exposed and control cultures were infected with the papovavirus simian virus (SV-) 40 (Strain RH 911) at a multiplicity of infection (M.O.I.) of 300-500 ID50. A strong dose-dependent 'enhancement' of cell transformation frequency occurred in kidney cultures of the Syrian golden hamster pretreated with extracts of airborne particulates and thereafter infected with the simian virus 40. It has to be emphasized, that very low quantities of extractable substances corresponding to particulates collected from 0.5 m3 of air, induced a strong highly significant increase in cell transformation frequency. Inoculation of transformed cells into syngeneic animals produced in a high percentage malignant tumors, mostly sarcomas.

Supernatants from quartz dust treated human macrophages stimulate cell proliferation of different human lung cells as well as collagen-synthesis of human diploid lung fibroblasts in vitro

Silicosis is a chronic lung disease, which is caused by inhalation of silica-containing dusts, leading to pulmonary fibrosis. Alveolar macrophages play a key-role in defence against these particles entering the lung. As a result of phagocytosis, the macrophages release mediators, which are involved in various processes of inflammation and immunological defence mechanisms. We established an in-vitro test system composed of human macrophages, human pneumocyte type II cells (line A-549), human diploid lung fibroblasts (line Wi38) and human tracheobronchial epithelial cells (line BEAS-2B). With this model, we were able to study the influence of various cytokines, produced by the macrophages, on cell proliferation and collagen synthesis (only fibroblasts) of the cells in our test-system. In this report, we will summarize data obtained from our in-vitro test system on two cytokines, which are thought to be important in pathogenesis of lung fibrosis: insulin-like growth factor-1 (IGF-1) and transforming growth factor-beta (TGF-beta).

Induction of sister chromatid exchanges (SCE) in human tracheal epithelial cells by the fractions PM-10 and PM-2.5 of airborne particulates

Recent epidemiological studies in the United States and in Europe indicate, that the coarse fraction (PM-10) of airborne particulates, smaller than 10 microm and particularly the fine fraction (PM-2.5) smaller than 2.5 microm are responsible for adverse health effects, causing an increasing morbidity and mortality. Furthermore, an association was reported between air pollution, especially the levels of the fine respirable particles and death from lung cancer. The epithelium of the respiratory tract is the major target of airborne particulates and the location of the most common cancer in man, bronchogenic carcinoma. The genotoxic activity of the coarse (PM-10) and the fine fraction (PM-2.5) of airborne particulates leading to mutation and cancer can be analyzed using in vitro models of human bronchoepithelial cells. In our study collection of the coarse (PM-10) and the fine fraction (PM-2.5) of airborne particulates was conducted in the winter of 1996 in the highly industrialized Rhine-Ruhr region (Germany). For collection we selected an urban area (Düsseldorf), an industrialized area Duisburg and a rural area (Borken). Airborne particulates were collected with a Low Volume M-10 dichotomous sampler (Graseby-Andersen) equipped with glass fiber filters. Chemical substances were extracted from filters with di-chloromethane and quantitatively transferred to dimethylsulfoxide (DMSO). As target cells for testing the genotoxic activity we used cultures of the human bronchioepithelial cell line (BEAS-2B). As a sensitive cytogenetic endpoint for evaluation of the genotoxic activity of extracts of airborne particulates we utilized the induction of 'sister chromatid exchanges' (SCE). The coarse fraction PM-10 and especially the fine fraction PM-2.5 of airborne particulates from all three locations caused a strong dose-related induction of 'sister chromatid exchanges'. The fine fractions PM-2.5 from the three locations exerted a stronger genotoxic activity than the corresponding coarse fractions PM-10. While airborne particulates from Düsseldorf and Duisburg revealed a comparable genotoxic activity, the samples from Borken disclosed a lower genotoxicity. It is important that especially the fine fraction PM-2.5, exerted a strong genotoxicity equivalent to substances of airborne particulates from less than 0.5 m3 of air. Results of this study and earlier reports demonstrate that the human tracheobronchial epithelial cell line (BEAS-2B) in vitro offer a reliable and sensitive in vitro model for genotoxicity testing of airborne particulates, especially of the coarse (PM-10) and fine fraction (PM-2.5).

A rapid method for detection of nongenotoxic carcinogens of environmental pollutants using synchronized V79 cells and flow cytometry

Synchronized V79 cells were treated before entering mitosis with known and suspicious mitotic arrestants and analyzed by flow cytometry and by light microscopy. Colcemid, nocodazole, vinblastine, diethylstilbestrol, triethyl lead and cadmium sulfate caused a dose dependent mitotic arrest of up to 80%, in comparison with 6% for the controls. Mixtures of polycyclic aromatic hydrocarbons and heterocyclic compounds induced a mitotic arrest of 50%-60%. Extracts of airborne particulates revealed a mitotic arrest of 10%-40%. In contrast, benzoquinone and hydroquinone led to a G2-block rather than to a mitotic arrest. Results of flow cytometry measurements correlated well with those obtained by light microscopy. Cell synchronization in combination with flow cytometry seems to be of considerable value as a rapid method for testing nongenotoxic agents with mitotic arresting activity.

Sister chromatid exchanges in rodent tracheal epithelium exposed in vitro to environmental pollutants

In our highly industrialized world, air pollution has become a major topic. The human respiratory tract is constantly exposed to air pollutants by inhalation. Besides gaseous pollutants airborne particulates are of great importance, containing a complex mixture of several hundred substances. The tracheobronchial epithelium is the major target site of airborne particulates as well as the origin of the most common cancer in man, the bronchogenic carcinoma. In our study we collected samples of airborne particulates in winter 1991 in the highly industrialized Rhine-Ruhr area (Germany) with a high-volume sampler on glass fiber filters. Airborne particulates were extracted with di-chloromethane and quantitatively transferred to dimethyl sulfoxide (DMSO) for tissue culture experiments. As target cells for genotoxicity testing we used cultures of rodent tracheal epithelial cells from the Syrian golden hamster and from the rat. Induction of "sister chromatid exchanges" (SCE) was utilized as a sensitive cytogenetic endpoint for evaluation of the genotoxic activity of extracts of airborne particulates. In presence of global extracts (GEX) we observed a dose-dependent, highly significant increase of SCE in tracheal epithelial cells of the Syrian golden hamster and of the rat. It is remarkable that even quantities of chemical substances equivalent to airborne particulates from less than 1 m3 of air were genotoxic. Results of this study and earlier reports demonstrate that rodent tracheal epithelial cells offer a reliable and sensitive in vitro model for genotoxicity testing of airborne particulates. Therefore, tracheal epithelial cells in vitro appear a meaningful alternative to other human and rodent cell culture systems which have been used for genotoxicity testing of air pollutants.

Assessment of cancer hazard from environmental pollution in Silesia

New concepts of cancer risk estimation have been developed during the past decade. Short-term bioassays dealing with mutagenicity and carcinogenicity of environmental samples are being replaced by more relevant molecular epidemiology studies. The general idea of using a battery of bioassays remains unchanged while the origin of tested samples is different. Instead of testing samples collected from the environment, body fluids or human cells from exposed populations are under investigation. This paper reviews the collaborative study on cancer risk assessment in highly polluted industrial region of Silesia in which both approaches had been employed during the 1985-1995 period. A potent carcinogenic activity of airborne pollutants was indicated in a battery of in vitro and in vivo short-term assays. These studies were followed by the molecular epidemiology study performed on human populations inhabiting the region of Silesia. An elevated damage of genetic material on the chromosome and/or DNA levels was observed in the Silesian populations as compared with proper rural controls.

Rodent tracheal epithelial cells in vitro: a comparative study of normal cells, enhanced growth variants, SV-40 transformed cells and their interactions

Tracheal epithelial cells of the golden Syrian hamster can be successfully cultivated in vitro and applied as a model system of respiratory tract epithelium. By morphology and growth characteristics of tracheal epithelial cells, "normal cells", "enhanced growth variants" and "transformed cells" were distinguished in vitro. Hamster tracheal epithelial cells, transformed by Simian virus (SV)-40 expressed in cell nuclei the specific tumor (T-) antigen and showed an accumulation of tumor suppressor protein p53 by immunofluorescence. Cocultivation of "enhanced growth variants" and of "transformed cells" on a "feeder layer" of normal hamster tracheal epithelial cells revealed remarkable differences in loss of "contact inhibition of growth". A "cytokine" released by NIH-3T3 cells stimulated cell proliferation and seems to be important for cell growth of hamster tracheal epithelial cells. Preliminary characterization of the "cytokine" disclosed a molecular weight of more than 30 kDa, a relative thermostability and a loss of activity by treatment with mercaptoethanol indicating disulfide bridges in a molecule.

Tumour necrosis factor-alpha induction by endotoxin-containing coal mine dusts in cultures of human macrophages and its effects on pneumocyte type II cells

Recent results indicate that tumour necrosis factor alpha (TNFalpha) may have an important role in the pathogenesis of silicosis. Supernatants of macrophages exposed to quartz and coal mine dust were tested for the presence of TNFalpha. Monocytes were isolated from peripheral blood and cultured for 10-14 days. After in vitro maturation of monocytes to cells with characteristics of macrophages, they were incubated with quartz dust DQ12 and various coal mine dusts from the Ruhr Valley for 24 hr. TNFalpha bioactivity in the supernatants of dust-treated macrophages was measured in a cytotoxicity bioassay with L929-mouse fibroblasts. Endotoxin, the lipopolysaccharide-containing cell wall component of Gram-negative bacteria, is the most important stimulator of TNFalpha induction in human macrophages. Suspensions of coal mine dusts from the Ruhr Valley and quartz dust DQ12 were therefore analysed for the presence of endotoxin by the very sensitive Limulus amoebocytes lysate test. Only a few suspensions of coal mine dusts from the Ruhr Valley contained endotoxin. Only endotoxin-containing dusts stimulated macrophages to produce TNFalpha. Incubating human pneumocytes type II (line A-549) with TNFalpha as the pure substance led to a transformation of these epithelial cells into spindle-shaped cells. This morphological transformation was accompanied by marked inhibition of pneumocyte type II proliferation.

Comparative genotoxicity testing of airborne particulates using rodent tracheal epithelial cells and human lymphocytes in vitro

In our study samples of airborne particulates were collected in the heavily industrialized Rhine-Ruhr region utilizing a high volume sampler HVS 150 (Ströhlein Instruments) equipped with glass fibre filters. Chemical substances were extracted from filters with dichloromethane and quantitatively transferred to dimethyl sulfoxide (DMSO) for tissue culture experiments. For detection of genotoxicity of extract of airborne particulates we utilized as a sensitive bioassay the induction of 'sister chromatid exchanges' (SCE) in cultures of human lymphocytes and of tracheal epithelial cells of the Syrian golden hamster. The extract of airborne particulates was added in various concentrations to cell cultures of human lymphocytes and hamster tracheal epithelial cells in presence of bromodeoxyuridine for 72 or 48 h, the last 3 h in presence of demecolcine or nocodazole, respectively. Extract of airborne particulates led in both test systems--human lymphocytes and tracheal epithelial cells of the hamster--to a dose-dependent, highly significant induction of 'sister chromatid exchanges'. Very low quantities of substances corresponding to airborne particulates from less than 1 m3 air were highly effective in both cell systems. In comparison, tracheal epithelial cells of the Syrian golden hamster revealed a higher sensitivity showing a steeper increase of 'sister chromatid exchanges' than human lymphocytes.

Inhibition of phagocytosis of human macrophages induced by airborne particulates

Human monocyte-derived macrophages isolated from peripheral blood were treated with different extracts of airborne particulates collected in the highly industrialized Rhine-Ruhr area. All tested extracts showed a substantial impairment of phagocytosis by inhibition of phagocytic activity as well as phagocytic capacity, while cell viability was rather well maintained. Significant reduction of phagocytosis already appeared at a concentration equivalent to extracted particulates from 3.8 m3 air. Having properties of alveolar macrophages, human monocyte-derived macrophage cultures may offer a reliable in vitro model for assessment of pulmonary toxicity by respirable pollutants.

Influence of airborne suspended matter on mitotic cell division

The effect of organic extracts of airborne suspended matter collected in the highly polluted industrial region of Silesia (Poland) on mitotic cell division was evaluated in the Chinese hamster V79 cell line. Crude benzene extracts as well as sequential elution solvent chromatography (SESC) fractions were investigated for their ability to affect the mitotic index, the proportion of anaphases-telophases to metaphases (AT/M ratio), the cloning efficiency and to produce aneuploid cells. The incidence of cell division disturbances in V79 cells exposed to extracts increased in a concentration-dependent manner. Mitotic arrest, manifested as a highly increased mitotic index and a concomitant decrease in the AT/M ratio, was found for the crude extract at a dose corresponding to 0.75 m3 of air. Comparable effects were noticed for SESC fraction 4, probably containing monophenol compounds. A strong dose-dependent reduction of cloning efficiency of V79 cells demonstrated cytotoxic activity of both the crude extract and fraction 4.

Genotoxicity of particulate emissions from gasoline-powered engines evaluated by short-term bioassays

Atmospheric pollutants, especially airborne particulates, contain a large number of genotoxic substances capable of inducing human health effects via inhalation. One important source of air pollutants are exhaust particles from automobile traffic. This concerns mainly diesel exhaust for which genotoxic properties are evident. With respect to particle emissions produced by gasoline-powered cars little information on a genotoxic potential is available. In this study 3 particulate emission extracts from different gasoline-powered cars driven with leaded or unleaded gasoline were investigated for cytotoxic and genotoxic activities by means of short-term bioassays using mammalian cell culture systems. All tested extracts were found to induce a broad spectrum of cytotoxic and genotoxic effects suggesting that gasoline exhausts are under high suspicion of contributing to health effects in human populations via air pollution.

Inhalation hazards from airborne particulates evaluated by in vitro cyto- and genotoxicity testing: a long-term study over a period of 14 years (1975-1988) from a highly industrialized area

26 samples of airborne particulates collected between 1975 and 1988 in the highly industrialized Rhine-Ruhr region were analyzed for cytotoxic and genotoxic activity. Samples were extracted by organic solvents and quantitatively transferred to dimethyl sulfoxide for tissue culture experiments. Cytotoxicity testing of samples revealed a dose related loss of cell viability of mouse and human macrophages as well as an impairment of phagocytosis. We observed a reduction of "plating efficiency" of rodent and human lung cell lines induced by extracts. In the presence of extracts we found an inhibition of DNA synthesis, alterations of cell cycle progression and diminished cell growth of rodent, primate and human tissue culture cells. Genotoxic potency of extracts caused dose dependently an induction of "sister chromatid exchanges" in human lymphocyte cultures, Chinese hamster cell line V 79 and human type II pneumocytes of line A 549. Furthermore, we observed by extracts "chromosomal aberrations" in human lymphocyte cultures and a strong "enhancement" of malignant cell transformation of SV40-infected Syrian hamster kidney cells.

Comparative study of sister-chromatid exchanges and chromosomal aberrations induced by airborne particulates from an urban and a highly industrialized location in human lymphocyte cultures

Cytogenetic effects induced by extracts of airborne particulates in human lymphocyte cultures were studied with regard to local and seasonal variations. Samples of airborne particulates were collected from an urban and a highly industrialized area in March and October, respectively. All extracts of particulates induced a significant increase of sister-chromatid exchanges (SCE) in a dose-dependent manner. Referring to the induction of sister-chromatid exchanges, local and seasonal differences were observed. Samples from the industrialized area revealed the highest activities. In addition, SCE rates found for March samples were always higher than those for October for both locations. Furthermore, a remarkable, significant induction of chromosomal aberrations occurred with all samples from both locations and sampling periods. Aspects of health risk evaluation for exposed human populations are discussed with respect to the observed cytogenetic effects of airborne particulates in human lymphocyte cultures.

Induction of C-type metaphases and aneuploidy in cultures of V79 cells exposed to extract of automobile exhaust particulates

An extract of particulate matter (EPM) from gasoline engine exhaust has been tested for its effect on cell viability and plating efficiency, and its ability to produce abnormal mitotic figures and numerical chromosome alterations using the Chinese hamster cell line V79. Within a defined concentration range of EPM (0.62-4.95 micrograms/ml), no significant loss of cell viability could be observed, whereas a strong dose-dependent reduction of plating efficiency occurred. This effect is attributed to the spindle-modifying ability of EPM as could be demonstrated by the induction of C-metaphases and a highly increased mitotic index. As a result of disturbances of the spindle apparatus, EPM was found to induce aneuploidy and polyploidy in a dose-dependent manner.

Cytogenetic effects of airborne particulate matter in human lymphocytes in vitro

City smog was collected in a heavily industrialized area and investigated for its ability to induce cytogenetic effects in human lymphocytes in vitro. Total extract of city smog was found to produce sister-chromatid exchanges and chromosomal aberrations in a dose-dependent manner. In addition cell-cycle delay was observed at higher concentrations of city smog extract. Results of cytogenetic testing are discussed with respect to cell-cycle kinetics.

[Biological effect of fine atmospheric dust extracts. IX. Quantitative cytologic study of the cytotoxic effect of fine atmospheric dust extracts on macrophages]

Macrophages of cell line IC-21 were exposed to extracts and fractions of two samples of city smog (CSE 16 and 17) from the heavy industrialized Rhine-Ruhr-area. Cytotoxic effects of extracts and fractions were analysed in various concentrations and periods of incubation. As cytotoxic parameters were determined frequencies of mitosis and pycnosis of nuclei as well as occurrence of multinucleated giant cells. An increasing dosage of noxae showed a reduction of mitotic rate, a rise of pycnosis of nuclei and of multinucleated giant cells. For both city smog extracts these effects depended on incubation period and concentration of noxae. While the global extract of city smog no. 16 was always more effective than its fractions, with city smog no. 17 the strongest alterations were demonstrable by its cyclohexane-fraction and partly by its methanol-fraction. Based on air volume of collection both samples of city smog revealed a comparable cytotoxic effect. In relation to benzo(a)pyrene-content, however, city smog no. 17 was considerable more cytotoxic than city smog no. 16. These results confirm again cytotoxicity of city smog. It can be assumed that both samples of city smog impair defense mechanisms of the lung.

[Biological effects of smog. VIII. Impulse cytophotometric cell cycle analysis of synchronized Syrian hamster kidney cell cultures (line 14-b)]

Syrian hamster kidney cultures of line 14-1b were synchronized by excess of thymidine. Thereafter in the phase of DNA synthesis cell cultures were exposed to extract and fractions of city smog, derived from a polluted area at the river Rhine and Ruhr. Using impulscytophotometry and estimation of mitotic frequency cell cycle analyses were conducted on synchronized exposed and control cultures. The total extract obtained by methanol treatment of city smog was further fractionated by organic solvents leading to fractions of cyclohexane, polyaromates and propanol. Cell cycle progression of synchronized cultures was inhibited in a dose dependent manner by increasing concentration of city smog extract and its fractions. This inhibition led to a prolongation of DNA synthetic phase and to an accumulation of cells in G2(+ M)-phase. The total cell cycle showed a prolongation of 3-5 h. The strongest effect was induced by the total extract. We have to emphasize that already amounts of city smog which were found in air volumes of 2-5 m3 exerted strong effects. With a declining sequence of toxicity followed the fractions of cyclohexane, propanol and of polyaromates. Our results show, that samples of city smog from polluted areas contain substances which induce heavy alterations in cell cycle progression of mammalian cells in vitro. These highly effective toxic substances are dangerous for human health, especially after a long-time exposition.

[Biological effect of smog extract. VII. Severe disorders of the cell cycle and its phases in kidney cultures as effected by extract and fractions of smog from a heavily industrialized area]

We analyzed the effect of airborne particulate matter, collected from the city of Duisburg on DNA-synthesis, mitotic rate and the cell cycle employing mammalian cells in vitro. As a test system we used logarithmically growing kidney cell cultures of the Syrian golden hamster (Cricetus aureatus). To elucidate alterations of DNA-synthesis and cell cycle under influence of extracts and fractions of city smog we used the autoradiographic method and the analytic procedure according to Quastler and Sherman. Extract and fractions induced a dose dependent decrease of DNA synthesizing cells, reduction of mitotic rate and very strong alterations of the cell cycle. The particular phases of the cell cycle were extended, partly abolished. We observed great differences concerning the effect of various fractions. The strongest effect was exerted by the total extract and the methanol-fraction. In this case the effective dosage was equivalent to an air volume of 2-5 cbm. With a declining sequence of toxicity followed the fractions of cyclohexane, propanol and of polyaromates. Results demonstrate that airborne particulate matter or city smog from industrialized areas contain substances which act strongly cytotoxic on mammalian cells in vitro and induce heavy alterations of the cell cycle. Therefore we have to expect, especially after long-term exposure also in human being health damages.

[Autoimmunity in patients with bronchogenic carcinomas: occurrence of antibodies against nuclear antigens, chromosomes and ds-deoxyribonucleic acid]

We report about occurrence of antinuclear antibodies (ANA), antibodies against chromosomes and ds-DNA in sera from patients with bronchogenic carcinomas of various histology. For detection of antibodies we used the method of indirect immunofluorescence. As antigenic substrates served cell cultures of kidneys from Cerc. aeth. and HeLa-cells. We found antinuclear antibodies in 79 sera from 133 sera of patients with bronchogenic carcinomas employing kidney cell cultures. The antinuclear antibodies of the 79 positive sera belong in 68 cases to immunglobuline class of IgG, in 15 cases to the class of IgM. Using positive sera we observed 4 patterns of nuclear fluorescence: homogeneous (diffuse), peripheral or rim-pattern, speckled and nucleolar. 32 of the 79 positive tumor sera contained also antibodies against the mitotic apparatus of kidney cell cultures. Applying HeLa cells as an antigenic substrate 62 of the 133 analyzed tumor sera showed antinuclear antibodies, in 16 of them we detected also antibodies against the mitotic apparatus of these cells. These 16 sera contained in 9 cases antichromocomal antibodies, in 7 cases antiperichromosomal antibodies when using spread chromosomes of HeLa-cells as a substrate. Antibodies directed against ds-DNA were seen in 39 of the 133 tumor sera utilizing hemoflagellate Crithidia luciliae as an antigenic substrate. We want to emphasize that about half of the patients containing antinuclear antibodies in their sera showed at the same time antibodies against ds-DNA and in one third of the cases we could demonstrate also antimitotic antibodies. Furthermore, we discuss significance of autoimmune phenomena in tumor diseases, especially in bronchogenic carcinomas.

Cytotoxic effects of air pollutants on mammalian cells in vitro

Extract and fractions of city smog collected from a heavy industrialized area caused in vitro dose-dependent reduction of cell survival of mouse macrophages and a growth inhibition of human fetal diploid lung fibroblasts. Great differences were observed in both cell systems between the total extract and its different fractions. Cytotoxicity declined in the sequence of total extract followed by fractions of cyclohexane, methanol, propanol and of polycyclic aromatic hydrocarbons. Our results illustrate that samples of city smog contain highly toxic substances for mammalian cells in vitro. Differences in cytotoxicity of particular fractions indicate that toxic agents belong to various classes of chemical substances.

Analysis of minimal functions of simian virus 40. 3. Evidence for "host cell repair" of oncogenicity and infectivity of UV-irradiated simian virus 40

The in vitro transforming capacity of simian virus 40 (SV40) for Syrian hamster cells is highly resistant to inactivation by UV light in comparison to infectivity. In the same cell system, we demonstrated a "host cell repair mechanism" sensitive to caffeine which is, to a large extent, responsible for the high resistance to UV inactivation of the transforming capacity of SV40. The survival of infectivity of UV-irradiated SV40 in CV-1 cells was also sensitive to caffeine, again indicating host cell repair. On the other hand, depression of normal cell DNA synthesis by hydroxyurea during the first 24 h postinfection only modestly reduced, and to a similar extent, the transforming capacity of UV-irradiated and nonirradiated SV40.

Analysis of minimal functions of simian virus 40. II. Enhancement of oncogenic transformation in vitro by UV irradiation

After light UV irradiation (5,000 to 10,000 ergs/mm(2)) "complete" and "defective" simian virus 40 (SV40) showed an enhancement of oncogenic transformation capacity in Syrian hamster kidney cells in vitro up to 180 and 270% of the controls, respectively. Simultaneously with the enhancement of transformation, an increase in T-antigen induction was observed in CV-1 cells infected with light UV-irradiated SV40; infectivity, however, was correspondingly reduced by 1 log(10). After strong UV irradiation (10,000 to 80,000 ergs/mm(2)) of "complete" and "defective" SV40, transformation capacity in vitro proved to be the most resistant viral function. It was only slightly reduced in comparison with a 4 to 5 log(10) reduction of infectivity. T-antigen induction of SV40 was also equally resistant to strong UV irradiation. We found no evidence of "multiplicity reactivation" involved in the high resistance of transformation capacity of SV40 after UV irradiation. Syrian hamster kidney cells transformed in vitro by UV-irradiated SV40 contained the SV40-specific T-antigen and showed the same morphology and growth characteristics as cells transformed by non-irradiated "complete" or "defective" SV40. They induced malignant tumors after subcutaneous inoculation into Syrian hamsters.