Catherine Aranyi

Metal toxicity for rabbit alveolar macrophages in vitro

Abstract A model system in vitro has been employed to assess the relative cytotoxic properties of soluble salts of metals that occur as environmental contaminants. Rabbit alveolar macrophages obtained by lung lavage were exposed in tissue culture for 20 hours to chlorides of Cd2+, Ni2+, Mn2+, and Cr3+ and to ammonium vanadate (VO3−). All metals except Cd2+ produced significant decreases in numbers of cells at concentrations that affected cell viability. Cd2+ was unique in decreasing cell viability without causing cell lysis. In comparing the relative cytotoxicity of the various metals, the number of viable cells remaining after 20 hours was expressed as a percent of the total number of cells in control cultures at 20 hours. Thus, the net number of viable cells was decreased to 50% of control at concentrations of 0.1 m m Cd2+ and VO3− or 4–5 m m Ni2+, Mn2+, and Cr3+. The specific activity of acid phosphatase, a lysosomal indicator enzyme, was also decreased at similar concentrations. Using scanning electron microscopy it was possible to correlate surface alterations with exposure concentrations and cell viabilities so as to suggest a mode and sequence of cell injury which may ultimately lead to cell death.

Cytotoxicity to alveolar macrophages of trace metals adsorbed on fly ash.

Fly ash fractionated into <2-, 2- to 5-, and 5- to 8-μm size ranges and coated on the surface with PbO, NiO, or MnO2 was used to examine the cytotoxic effects in vitro of particle concentration and size to alveolar macrophages (AM). For the various fly-ash samples, statistically significant decreases were demonstrated in viability, total protein, and lactate dehydrogenase activity with increasing concentration and decreasing particle size. The toxic effect was not due to solubilization of the test metals in the media since no toxicity could be demonstrated using particle-free leaches. The percentage of metal adsorbed on the fly ash varied within a narrow range and therefore at a given concentration the AM were exposed to fairly constant amounts of the test elements irrespective of particle size. Thus cytotoxicity is particle size as well as dose dependent and the greater toxicity of the smaller particles appears to be due to their larger surface area.

Effects of subchronic exposure to a mixture of O3, SO2, and (NH4)2SO4 on host defenses of mice

Mice exposed 5 h/d, 5 d/wk up to 103 d, to 0.2 mg O3/m3 or to a mixture of O3, 13.2 mg SO2/m3, and 1.04 mg (NH4)2SO4 aerosol/m3 showed significantly greater susceptibility to group C streptococcal aerosol infection relative to filtered air controls. Pulmonary bactericidal activity by alveolar macrophages was significantly enhanced in the lungs of mice exposed to the mixture relative to those inhaling filtered air or O3 alone. The total number and distribution of the free cells lavaged from the lungs, as well as cellular ATP levels, did not change due to the pollutant exposures. In vitro cytostasis in tumor target cells cocultured with peritoneal macrophages from the exposed mice was significantly enhanced in the O3-exposed and in the mixture-exposed treatment groups relative to controls and also in the mixture-exposed relative to the O3-exposed group when a target-to-effector-cell ratio of 1:10 was used; no such effects were observed when this ratio was 1:20. Splenic T-lymphocyte function, as measured by blastogenesis to mitogens and alloantigens, was affected by exposure to O3 and/or the mixture, although the patterns of effects were qualitatively different. Splenic B-cell function and macrophage antigen processing, as measured by the generation of antibody plaque-forming cells, was unaffected by exposure.

The Effects of Inhalation of Organic Chemical Air Contaminants on Murine Lung Host Defenses

The potential health hazards of exposure to threshold limit value (TLV) concentrations of acetaldehyde, acrolein, propylene oxide, chloroform, methyl chloroform, carbon tetrachloride, allyl chloride, methylene chloride, ethylene trichloride, perchloroethylene, benzene, phenol, monochlorobenzene, and benzyl chloride, compounds which may be present in the ambient or work room atmosphere were investigated. The effects of single and multiple 3-hr inhalation exposures were evaluated in mice by monitoring changes in their susceptibility to experimentally induced streptococcus aerosol infection and pulmonary bactericidal activity to inhaled Klebsiella pneumoniae. When significant changes in these parameters were found, further exposures were performed at reduced vapor concentrations until the no-measurable-effect level was reached. Multiple exposures on 5 consecutive days were then performed at this concentration. Significant increases in susceptibility to respiratory streptococcus infection were observed after single 3-hr exposure to TLV concentrations of methylene chloride, perchloroethylene, and ethylene trichloride. For methylene chloride and perchloroethylene, these exposure conditions also resulted in significantly decreased pulmonary bactericidal activity.

Evaluation of host resistance and immune function in cadmium-exposed mice☆

Adult female B6C3F1 mice received distilled water only or water containing 10, 50, or 250 ppm of cadmium chloride (CdCl2) for 90 days. Body weights were measured weekly. On selected days during exposure and on Day 91, Cd tissue concentrations were measured along with changes in primary antibody responses. On Day 91 mice also received a primary challenge with various infectious agents. T- and B-cell mitogenesis, natural killer (NK) cell function, delayed type hypersensitivity (DTH) as well as macrophage bactericidal activity, and phagocytosis were measured. There was no change in body weight gain, organ weights, or in humoral immunity during treatment even though cadmium had accumulated in significant quantities in the tissues. Compared with controls, exposure to cadmium had no statistically significant effect on mortality and mean survival time following primary or secondary challenge with any of the infectious agents. However, there was a dose-related, increased susceptibility to Herpes simplex type 2 virus. T- and B-lymphocyte proliferation was significantly reduced, and macrophage phagocytosis was significantly increased following cadmium exposure. NK cell activity was augmented, but not significantly. Macrophage bactericidal activity and DTH were not significantly altered.

Effects of arsenic trioxide inhalation exposure on pulmonary antibacterial defenses in mice

The effects of single and multiple (5 and 20) 3-h inhalation exposures to aerosols of arsenic trioxide on the pulmonary defense system of mice were investigated. Arsenic trioxide mist was generated from an aqueous solution and dried to produce particulate aerosols of 0.4 micron mass median aerodynamic diameter. Aerosol mass concentration ranged from 125 to 1000 micrograms As/m3. Effects of the exposures were evaluated by determination of changes in susceptibility to experimentally induced streptococcal aerosol infection and in pulmonary bactericidal activity to 35S-labeled Klebsiella pneumoniae. Significant increases in mortality due to the infectious challenge and decreases in bactericidal activity were seen after single 3-h exposures to 270, 500, and 940 micrograms As/m3. Similarly, 5 or 20 multiple 3-h exposures to 500 micrograms As/m3 produced consistently significant increases in mortality and decreases in pulmonary bactericidal activity. At 125 or 250 micrograms As/m3, a decrease in bactericidal activity was seen only after 20 exposures to 250 micrograms/m3. Results from earlier studies with an arsenic-containing copper smelter dust were compared to these data. The possibility of the development of adaptation during multiple exposures to arsenic trioxide is also considered.

The effect of dimethylnitrosamine on host resistance and immunity

Adult female B6C3F1 mice were injected ip with 0.2 ml phosphate-buffered saline (PBS) only or PBS containing 1.5, 3, or 5 mg dimethylnitrosamine (DMN)/kg body wt daily for 14 days. On Day 16, mice were evaluated for changes in immune status as measured by the antibody response to sheep red blood cells (SRBCs), blastogenesis to T- and B-cell mitogens, natural killer (NK) cell function, delayed hypersensitivity, and alveolar macrophage (AM) bactericidal activity; and for changes in host resistance following challenge with various microorganisms or tumor cells. DMN-exposed animals exhibited reduced humoral antibody responses, T-cell mitogenesis, and AM bactericidal activity. B-cell mitogenesis, NK cell activity, and delayed hypersensitivity were increased. Resistance to challenge with Listeria monocytogenes, Trichinella spiralis, or Herpes simplex types 1 or 2 virus (HSV-1, HSV-2) was not significantly impaired, while that to Streptococcus zooepidemicus and influenza virus was significantly reduced. Resistance to B16-F10 tumor challenge was enhanced following DMN exposure. The data show that DMN treatment altered humoral immunity and antibody-mediated host defense mechanisms. Increased NK cell activity may account for the increased resistance to challenge with Herpes virus and B16-F10 tumor cells.

Tumor induction in F344/N rats and B6C3F1 mice following inhalation exposure to ethylbenzene

Carcinogenesis studies of ethylbenzene were conducted because of its extensive use as a solvent and because it is structurally similar to the known carcinogen benzene. Groups of 50 male and 50 female Fischer rats and B6C3F1 mice were exposed to ethylbenzene by inhalation at 0, 75, 250, and 750 ppm 6 h per day, 5 days per week, for 2 years. The dose levels were selected based on the results of 13-week studies. In the 750 ppm group of male and female rats, body weights were slightly lower and incidences of renal hyperplasia and tubular neoplasms were significantly increased compared with controls. Incidence of testicular tumors was also significantly increased in male rats. Survival and body weights of the exposed groups of male and female mice and controls were comparable. Incidences of alveolar epithelium metaplasia, alveolar/bronchiolar adenoma, and hepatocyte hypertrophy and necrosis were significantly increased in the 750 ppm male mice and incidences of liver eosinophilic foci and hepatocellular neoplasms were significantly increased in the 750 ppm female mice compared with controls. Ethylbenzene is carcinogenic inducing neoplasms in kidneys and testes in Fischer rats and in lungs in male and liver in female B6C3F1 mice.

Health effects of long-term inhalation of sulfuric acid mist-carbon particle mixtures.

The effects of exposures of mice 3 hr/day, 5 days/week for up to 20 weeks to 1.4 mg/m/sup 3/ sulfuric acid mist and 1.5 mg/m/sup 3/ carbon particle mixtures as well as 1.5 mg/m/sup 3/ carbon only were investigated. The immunologic state of the animals was examined directly by the primary response of spleen cells after specific antigen stimulation, and indirectly by infectivity studies. A quantitative measure of the effects on the immune system without the antigenic stimulation was obtained by determination of serum immunoglobulin concentrations. Significant alterations of immunoglobulin titer, depression of primary antibody response in spleen cell antigenic stimulation, and decreased resistance to respiratory infection as measured by mortality, survival time, and pulmonary consolidation after 20 weeks of exposure to acid mist and carbon particle mixtures were noted. In addition, bactericidal capacity of lungs was reduced in mice exposed to either sulfuric acid and carbon mixtures or to carbon alone, and subtle morphological changes in the respiratory tract were detected by scanning electron microscopy. Thus the alterations of the defense system suggest that prolonged exposure to low concentrations of sulfuric acid and carbon particle mixtures reduces the ability of mice to resist the secondary stress of respiratory infection.

Effects of toluene inhalation on pulmonary host defenses of mice

The potential hazards of exposure to vapor-phase toluene on pulmonary host defenses were evaluated. Mice exposed to concentrations ranging from 2.5-500 ppm, including the threshold limit value level of 100 ppm, exhibited increased susceptibility to respiratory infection with Streptococcus zooepidemicus. The no-measurable-effect level for single, as well as for 5 exposures was 1 ppm. Significantly decreased pulmonary bactericidal activity was observed after single exposures to 500, 250, 100 and 2.5 ppm toluene, and after 5 daily 3-h exposures to 1.0 ppm of toluene. A 20-exposure study with toluene at 1 ppm produced no changes in either of the 2 assays.