Effects of an environmentally relevant PCB-mixture on immune function, clinical chemistry, and thyroid hormone levels in adult female B6C3F1 mice.

Polychlorinated biphenyls (PCBs) have been assessed for immunotoxicity; however, humans and wildlife are exposed to multiple PCBs environmentally. Therefore, the aim of this study was to examine the effects of a complex 37 PCB congener mixture identified in blubber specific to dolphins residing in the estuarine waters of Charleston, South Carolina. Immunotoxicity was determined in adult female B6C3F1 mice by assessing lymphocyte proliferation, splenic and thymic immunophenotypes, and IgM production. Mice were exposed via oral gavage to the PCB-mixture (0, 1.8, 3.6, 7.1, or 14.3 mg/kg/day) for 28 days to yield a targeted total administered dose (TAD) 0, 50, 100, 200, or 400 mg/kg. Significant increased liver weight occurred at the highest treatment. IgM production was suppressed compared to control for all treatments. Numbers of thymic CD4+/CD8+, CD4-/CD8-, and CD4+/CD8- cells were not altered, but numbers of thymic CD4-/CD8+ cells were significantly increased in the highest treatment. Lymphocyte proliferation was not markedly affected by any treatment. The numbers of splenic CD4/CD8 T-cells or MHCII+ cells were not significantly changed. Humoral immunity using the plaque-forming cell assay for determining the specific IgM antibody-forming cell response appeared to be the most sensitive endpoint affected. As the lowest concentration tested resulted in decreased IgM production and total and free thyroxine (T4) serum levels a NOAEL was not identified. The calculated ED50 for suppression of IgM production was 2.4 mg/kg/day.

Wastewater-based epidemiology pilot study to examine drug use in the Western United States.

The extent of prescription and illicit drug abuse in geographically isolated rural and micropolitan communities in the intermountain western United States (US) has not been well tracked. The goal of this pilot study was to accurately measure drug dose consumption rates (DCR) between two select populations, normalize the data and compare the DCRs to similar communities. To learn about patterns of drug abuse between the two disparate communities, we used the emergent field of wastewater-based epidemiology (WBE). A rapid, quantitative and systematic process for the determination of multiple classes of prescribed and illicit drugs was applied to influent wastewater samples. Influent samples were collected over the course of three months (April to June 2019) at two wastewater treatment plants representing a small urban and a rural community. Collection of sewage influent included 24-h composite samples and the use of polar organic chemical integrative samplers (POCIS), time-weighted samplers. Using the results from the composite sampling data, DCRs per 1000 population could be calculated from the concentration data and the use of excretion correction factors. The following 18 compounds: amphetamine, methamphetamine, MDA, MDMA, morphine, 6-acetylmorphine, methadone, EDDP, codeine, benzoylecgonine, hydrocodone, hydromorphone, oxycodone, noroxycodone, ketamine, fluoxetine, tramadol, and ritalinic acid; represent a subset of the targeted analytes that were consistently measured at detectable concentration levels, and present at both sites. Following normalization of the drug measurements to influent flow rates and per capita, the small urban community demonstrated greater collective excretion rates (CER) than the rural community, with the exceptions of amphetamine and methamphetamine.

Synthetic secoisolariciresinol diglucoside (LGM2605) inhibits Libby amphibole fiber-induced acute inflammation in mice.

BACKGROUND: Exposure to the Libby amphibole (LA) asbestos-like fibers found in Libby, Montana, is associated with inflammatory responses in mice and humans, and an increased risk of developing mesothelioma, asbestosis, pleural disease, and systemic autoimmune disease. Flaxseed-derived secoisolariciresinol diglucoside (SDG) has anti-inflammatory, anti-fibrotic, and antioxidant properties. We have previously identified potent protective properties of SDG against crocidolite asbestos exposure modeled in mice. The current studies aimed to extend those findings by evaluating the immunomodulatory effects of synthetic SDG (LGM2605) on LA-exposed mice. METHODS: Male and female C57BL/6 mice were given LGM2605 via gavage initiated 3 days prior to and continued for 3 days after a single intraperitoneal dose of LA fibers (200 µg) and evaluated on day 3 for inflammatory cell influx in the peritoneal cavity using flow cytometry. RESULTS: LA exposure induced a significant increase (p < 0.0001) in spleen weight and peritoneal influx of white blood cells, all of which were reduced with LGM2605 with similar trends among males and females. Levels of peritoneal PMN cells were significantly (p < 0.0001) elevated post LA exposure, and were significantly (p < 0.0001) blunted by LGM2605. Importantly, LGM2605 significantly ameliorated the LA-induced mobilization of peritoneal B1a B cells. CONCLUSIONS: LGM2605 reduced LA-induced acute inflammation and WBC trafficking supporting its possible use in mitigating downstream LA fiber-associated diseases. SUMMARY: Following acute exposure to Libby amphibole (LA) asbestos-like fibers, synthetic SDG (LGM2605), a small synthetic molecule, significantly reduced the LA-induced increase in spleen weight and peritoneal inflammation in C57BL/6 male and female mice. Our findings highlight that LGM2605 has immunomodulatory properties and may, thus, likely be a chemopreventive agent for LA-induced diseases.

Nevada desert dust with heavy metals suppresses IgM antibody production.

Systemic health effects from exposure to a complex natural dust containing heavy metals from the Nellis Dunes Recreation Area (NDRA) near Las Vegas, NV, were evaluated. Several toxicological parameters were examined following lung exposure to emissive dust from three geologic sediment types heavily used for recreational off-road activities: yellow sand very rich in arsenic (termed CBN 5); a shallow cover of loose dune sand overlying a gravelly subsoil bordering dune fields (termed CBN 6); and brown claystone and siltstone (termed CBN 7). Adult female B6C3F1 mice were exposed by oropharyngeal administration to these three types of geogenic dusts at 0.01-100 mg of dust/kg of body weight, once per week for four weeks. The median grain sizes were 4.6, 3.1, and 4.4 µm, for CBN 5, 6, and 7, respectively. Each type of dust contained quantifiable amounts of aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, arsenic, strontium, cesium, lead, uranium, and others. Descriptive markers of immunotoxicity, neurotoxicity, hematology, and clinical chemistry parameters were assessed. Notable among all three CBN units was a systemic, dose-responsive decrease in antigen-specific IgM antibody responses. Geogenic dust from CBN 5 produced more than a 70% suppression in IgM responses, establishing a lowest adverse effect level (LOAEL) of 0.01 mg/kg. A suppression in IgM responses and a corresponding increase in serum creatinine determined a LOAEL of 0.01 mg/kg for CBN 6. The LOAEL for CBN 7 was 0.1 mg/kg and also was identified from suppression in IgM responses. These results are of concern given the frequent off-road vehicle traffic and high visitor rates at the NDRA, estimated at 300,000 each year.

Comparative health effects in mice of Libby amphibole asbestos and a fibrous amphibole from Arizona.

This project developed from studies demonstrating that Libby Amphibole Asbestos (LAA) causes a non-typical set of health outcomes not generally reported for asbestos, including systemic autoimmunity and an unusual and devastating lamellar pleural thickening that progresses to severe pulmonary dysfunction and death. Further, mineral fiber mixtures with some similarities to LAA have recently been discovered in southern Nevada and northwestern Arizona, where the material exists in extensive recreational areas and is present in yards, roads, parking lots and school yards. The objective was to compare the health outcomes in mice exposed to either LAA or the fibrous amphiboles collected in Arizona at the Lake Mead National Recreational Area at very low doses to represent environmental exposures. In this study, the fibrous amphibole asbestos sample from Arizona (AzA) is composed of winchite (69%), actinolite (22%), and non-amphibole minerals (9%) and has a mean aspect ratio of 16.7±0.9. Fibrous amphibole asbestos from Libby (LAA) is composed of winchite (70%), richterite (9%), tremolite (5%), and non-amphibole minerals (16%) with a mean aspect ratio of 8.4±0.7. C57BL/6 mice were exposed by oropharyngeal aspiration to fiber suspensions at a very low dose of 3µg/mouse. After seven months, both LAA- and AzA-exposed mice had indices of chronic immune dysfunction related to a TH17 cytokine profile, with B cell activation, autoantibody production and proteinuria, suggesting kidney involvement. In addition, both exposures led to significant lung and pleural fibrosis. These data suggest that there is risk of pulmonary disease and autoimmune outcomes with environmental exposure to amphibole asbestos, and that this is not limited to Libby, Montana.

Health effects following subacute exposure to geogenic dust collected from active drainage surfaces (Nellis Dunes Recreation Area, Las Vegas, NV).

The specific health effects of direct inhalation of fine minerogenic dusts generated by natural soil surfaces remain poorly known and relatively little researched. To learn more about this exposure and its contribution to human health effects, we surveyed surface sediment and characterized dust from the Nellis Dunes Recreation Area (NDRA) in Clark County, Nevada, a popular off-road vehicle (ORV) recreational site. Dry drainage systems at NDRA are commonly used as natural trail systems for ORV recreation; these surfaces also are characterized by high concentrations of heavy metals. Geogenic dust with a median diameter of 4.05 µm, collected from drainage surfaces at NDRA contained a total elemental concentration of aluminum (79,651 µg/g), vanadium (100 µg/g), chromium (54 µg/g), manganese (753 µg/g), iron (33,266 µg/g), cobalt (14 µg/g), copper (37 µg/g) zinc (135 µg/g), arsenic (71 µg/g), strontium (666 µg/g), cesium (15 µg/g), lead (34 µg/g), and uranium (54.9 µg/g). Adult female B6C3F1 mice exposed via oropharyngeal aspiration to 0.01-100 mg dust/kg body weight, four times, a week apart, for 28-days, were evaluated for immuno- and neurotoxicological outcomes 24 h after the last exposure. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100 mg/kg. Splenic lymphocytic subpopulations, hematological and clinical chemistry parameters were affected. In brain tissue, antibodies against NF-68, and GFAP were not affected, whereas IgM antibodies against MBP were reduced by 26.6% only in the highest dose group. A lowest observed adverse effect level (LOAEL) of 0.1 mg/kg/day and a no observed adverse effect level (NOAEL) of 0.01 mg/kg/day were derived based on the antigen primary IgM responses after subacute exposure to this geogenic dust.

Health effects from exposure to atmospheric mineral dust near Las Vegas, NV, USA.

Desert areas are usually characterized by a continuous deposition of fine airborne particles. Over time, this process results in the accumulation of silt and clay on desert surfaces. We evaluated health effects associated with regional atmospheric dust, or geogenic dust, deposited on surfaces in the Nellis Dunes Recreation Area (NDRA) in Clark County, Nevada, a popular off-road vehicle (ORV) recreational site frequented daily by riders, families, and day campers. Because of atmospheric mixing and the mostly regional origin of the accumulated particles, the re-suspended airborne dust is composed of a complex mixture of minerals and metals including aluminum, vanadium, chromium, manganese, iron, cobalt, copper, zinc, arsenic, strontium, cesium, lead, uranium, and others. Geogenic dust with a median diameter of 4.1 µm was administered via oropharyngeal aspiration to female B6C3F1 mice at doses of 0.01 to 100 mg dust/kg body weight, four times, a week apart, for 28-days. Immuno- and neurotoxicological outcomes 24 h following the last exposure were evaluated. Antigen-specific IgM responses were dose-responsively suppressed at 0.1, 1.0, 10 and 100 mg/kg/day. Splenic and thymic lymphocytic subpopulations and natural killer cell activity also were significantly reduced. Antibodies against MBP, NF-68, and GFAP were not affected, while brain CD3+ T cells were decreased in number. A lowest observed adverse effect level (LOAEL) of 0.1 mg/kg/day and a no observed adverse effect level (NOAEL) of 0.01 mg/kg/day were derived based on the antigen-specific IgM responses.

Developmental immunotoxicity (DIT): assays for evaluating effects of exogenous agents on development of the immune system.

Developmental immunotoxicity (DIT) occurs when exposure to environmental risk factors prior to adulthood, including chemical, biological, physical, or physiological factors, alters immune system development. DIT may elicit suppression, hyperactivation, or misregulation of immune responses and may present clinically as decreased resistance to pathogens, allergic and autoimmune diseases, and inflammatory diseases. Immunotoxicity testing guidelines established by the Environmental Protection Agency for adult animals (OPPTS 8703.7800) require functional tests and immunophenotyping that are suitable for detecting immunomodulation, especially immunosuppression. However, evaluating immune function in offspring that are not fully immunocompetent yields results that are challenging to interpret. Therefore, this unit will describe an optimum exposure scenario, reference two assays (immunophenotyping and histopathology) appropriate for detecting immunomodulation in weaning-age offspring, and reference four assays (immunophenotyping, histopathology, T cell-dependent antibody responses, and delayed-type hypersensitivity) appropriate for detecting immunomodulation in immunocompetent offspring. The protocol also will reference other assays (natural killer cell and cytotoxic T lymphocyte) with potential utility for assessing DIT.

Immune function in female B(6)C(3)F(1) mice is modulated by DE-71, a commercial polybrominated diphenyl ether mixture.

Polybrominated diphenyl ethers (PBDEs) are an important class of flame-retardants that are environmentally persistent and bioaccumulative. Toxicity of these compounds has become a concern because detectable levels of PBDEs are present in humans and wildlife and they are structurally similar to polychlorinated biphenyls (PCBs). This study examined the effects of the commercial penta-BDE mixture, DE-71, in adult female B(6)C(3)F(1) mice on hematology, serum clinical chemistry, thyroid hormones, tissue histology, and several immunotoxicity end-points (lymphocyte proliferation, NK cell activity, splenic immunophenotypes, and SRBC-specific-IgM production). Mice were exposed via oral gavage for 28 days to achieve total administered doses (TAD) of 0, 0.5, 5, 50, or 100 mg/kg. No changes in histology, clinical chemistry, body or organ weights were observed. Serum total T3 and T4 levels were not altered by any of the DE-71 treatments. Peripheral blood monocyte numbers were decreased by the 0.5, 5, and 50 mg/kg treatments, but not by the 100 mg/kg TAD concentration. Compared to controls, mitogen-stimulated T- and B-cell proliferation was increased by the 100 mg/kg TAD concentration (ED(50) = 60 mg/kg TAD [2.14 mg/kg/day] and 58 mg/kg TAD [2.57 mg/kg/day], respectively). NK cell activity was decreased compared to controls by the 100 mg/kg TAD concentration (ED(50) = 20 mg/kg TAD [0.7 mg/kg/day]). No alterations were noted in thymic T-cell populations or in SRBC-specific-IgM production. Numbers of CD19(+)CD21(-), CD19(+)CD21(+), CD4(+)CD8(-), CD4(-)CD8(+), CD4(-)CD8(-), and MHC-II(+) cells in the spleen were not affected. However, the numbers of splenic CD4(+)CD8(+) cells were decreased compared to the controls by 0.5, 5, and 100 mg/kg TAD. This study provides an assessment of the systemic toxicity and immunotoxicity of DE-71, and indicates that immune parameters are modulated at exposure concentrations lower than previously reported.

Current status of developmental immunotoxicity: early-life patterns and testing.

Developmental immunotoxicity (DIT) occurs when exposure to environmental risk factors prior to adulthood, including chemical, biological, physical, or physiological factors, alters immune system development. DIT may elicit suppression, hyperactivation, or misregulation of immune responses and therefore may present clinically as decreased resistance to pathogens, allergic and autoimmune diseases, and inflammatory diseases. When evaluating DIT in an animal model, specific endpoints are assessed, which can reveal the potential for a risk factor to alter immune system development. However, linking DIT evaluation in an animal model with clinical realities observed in human populations requires that DIT testing regimens evaluate critical windows in immune system development. In addition, pathways leading to DIT may not be apparent without the stressors that induce aberrant and detectable responses. This review contains brief descriptions of recently published work that addresses disease patterns associated with DIT and solutions for altering such patterns of disease. We also comment on gaps between DIT testing in animal models and the clinical manifestation of immune-based diseases in children that can be filled by a better understanding of critical windows in immune system development and DIT testing that includes multiple functional assays.

Effects of environmentally-relevant levels of perfluorooctane sulfonate on clinical parameters and immunological functions in B6C3F1 mice.

In the first part of a series of studies to account for perfluorooctane sulfonate (PFOS)-induced sheep red blood cell (SRBC)-specific immunoglobulin M (IgM) antibody suppression in mice, a survey of clinical and immunotoxicological endpoints was examined. Adult female B6C3F1 mice were exposed orally for 28 days to a total administered dose (TAD) of 0, 0.1, 0.5, 1, or 5 mg PFOS/kg. Uterus wet weight was significantly decreased compared with control at the 5 mg/kg dose. No indications of wasting syndrome, malnutrition, alteration of thyroid homeostasis, or signs of overt toxicity were observed. Numbers of splenic CD19+/CD21⁻, CD19+/CD21+, B220+/CD40+, CD4+/CD154⁻, CD4+/CD154+, and MHC-II+ cells were not altered. Additionally, ex vivo interleukin-4 (IL-4), IL-5, and IL-6 production by in vitro anti-CD3- or phorbol myristate acetate-stimulated CD4+ T-cells was not affected. Ex vivo IL-6 production by B-cells was significantly increased by in vitro stimulation with either anti-CD40 or lipopolysaccharide. Increased IL-6 production by B-cells was the most sensitive endpoint assessed resulting in alterations at the lowest dose tested (0.1 mg/kg TAD) following anti-CD40 stimulation. Further studies are required to characterize effects on inflammatory markers such as IL-6 at environmentally relevant concentrations of PFOS and to determine the key events associated with PFOS-induced IgM suppression to address potential human health risks.

Discouraging academic dishonesty in online courses.

With the development of distance education and blended course delivery formats, our faculty faced new issues related to academic integrity in online testing. Current students often differ in their understanding of what is appropriate academic behavior and what is considered cheating. Enhancing quiz formats and educating faculty and students about academic integrity policies has minimized the situation in our program.

Assessment of trichloroethylene (TCE) exposure in murine strains genetically-prone and non-prone to develop autoimmune disease.

There is increasing laboratory and epidemiologic evidence relating exposure to trichloroethylene (TCE) with autoimmune disease including scleroderma and lupus. New Zealand Black/New Zealand White (NZBWF1) and B6C3F1 mice were exposed to TCE (0, 1, 400 or 14,000 ppb) via drinking water for 27 or 30 weeks, respectively. NZBWF1 mice spontaneously develop autoimmune disease while B6C3F1 mice, a standard strain used in immunotoxicology testing, are not genetically prone to develop autoimmune disease. During the TCE exposure period, serum levels of total IgG, and autoantibodies (anti-ssDNA, -dsDNA, and -glomerular antigen [GA]) were monitored. At the termination of the study, renal pathology, natural killer (NK) cell activity, total IgG levels, autoantibody production, T-cell activation, and lymphocytic proliferative responses were evaluated. TCE did not alter NK cell activity, or T- and B-cell proliferation in either strain. Numbers of activated T-cells (CD4+/CD44+) were increased in the B6C3F1 mice but not in the NZBWF1 mice. Renal pathology, as indicated by renal score, was significantly increased in the B6C3F1, but not in the NZBWF1 mice. Serum levels of autoantibodies to dsDNA and ssDNA were increased at more time points in B6C3F1, as compared to the NZBWF1 mice. Anti-GA autoantibodies were increased by TCE treatment in early stages of the study in NZBWF1 mice, but by 23 weeks of age, control levels were comparable to those of TCE-exposed animals. Serum levels anti-GA autoantibodies in B6C3F1 were not affected by TCE exposure. Overall, these data suggest that TCE did not contribute to the progression of autoimmune disease in autoimmune-prone mice during the period of 11-36 weeks of age, but rather lead to increased expression of markers associated with autoimmune disease in a non-genetically prone mouse strain.

N,N,-diethyl-m-toluamide (DEET) suppresses humoral immunological function in B6C3F1 mice.

N,N-diethyl-meta-toluamide (DEET) is a particularly effective broad-spectrum insect repellent used commonly in recreational, occupational and military environments. Due to its widespread use and suggested link to Gulf War Illness, this study examined the immunotoxicity of DEET. Adult female B6C3F1 mice were injected sc for 14 days with DEET at 0, 7.7, 15.5, 31, or 62 mg/kg/day. Due to differences in the dermal absorption of DEET between mice and humans, this study eliminated this confounding factor by utilizing sc injection and measured circulating blood levels of DEET to assess bioavailability from sc administration. Effects on lymphocyte proliferation, natural killer cell activity, thymus and spleen weight and cellularity, the antibody plaque-forming cell (PFC) response, and thymic and splenic CD4/CD8 lymphocyte subpopulations were assessed 24 h after the last dose. No effect was observed in lymphocyte proliferation, natural killer cell activity, thymic weight, splenic weight, thymic cellularity, or splenic cellularity. Significant decreases were observed in the percentage of splenic CD4-/CD8- and CD4+/CD8- lymphocytes but only at the 62 mg DEET/kg/day treatment level and not in absolute numbers of these cells types. Additionally, significant decreases in the antibody PFC response were observed following treatment with 15.5, 31, or 62 mg DEET/kg/day. Pharmacokinetic (PK) data from the current study indicate 95% bioavailability of the administered dose. Therefore, it is likely that DEET exposure ranges applied in this study are comparable to currently reported occupational usage. Together, the evidence for immunosuppression and available PK data suggest a potential human health risk associated with DEET in the occupational or military environments assuming similar sensitivity between human and rodent responses.

Developmental toxicity in white leghorn chickens following in ovo exposure to perfluorooctane sulfonate (PFOS).

Studies show that perfluorinated compounds cause various toxicological effects; nevertheless, effects on immune function and developmental endpoints have not been addressed at length. This study examined the effects of perfluorooctane sulfonate (PFOS) in white leghorn hatchlings on various developmental, immunological, and clinical health parameters. In addition, serum PFOS concentrations were determined by LC/MS/MS. Embryonic day (ED) 0 eggs were injected with either safflower oil/10% DMSO (control, 0mg/kg egg wt) or PFOS in safflower oil/10% DMSO at 1, 2.5, or 5mg/kg egg wt, and the chicks were grown to post-hatch day (PHD) 14. Treatment with PFOS did not affect hatch rate. Following in ovo exposure chicks exhibited increases in spleen mass at all treatment levels, in liver mass at 2.5 and 5mg/kg egg wt, and in body length (crown-rump length) at the 5mg/kg treatment. Right wings were shorter in all treatments compared to control. Increases in the frequency of brain asymmetry were evident in all treatment groups. SRBC-specific immunoglobulin (IgM and IgY combined) titers were decreased significantly at all treatment levels, while plasma lysozyme activity was increased at all treatment levels. The PHA skin test response decreased in relation to increasing PFOS dose. Serum concentrations where significant immunological, morphological, and neurological effects were observed at the lowest dose (1mg/kg egg wt) averaged 154 ng PFOS/g serum. These concentrations fall within environmental ranges reported in blood samples from wild caught avian species; thereby, verifying that the environmental egg concentrations used for the injections do indeed relate to serum levels in hatchlings that are also environmentally relevant. These data indicate that immune alterations and brain asymmetry can occur in birds following in ovo exposure to environmentally relevant concentrations of PFOS and demonstrates the need for further research on the developmental effects of perfluorinated compounds in various species.

Lifetime exposure to trichloroethylene (TCE) does not accelerate autoimmune disease in MRL +/+ mice.

A genetically-prone murine lupus model was used to assess the developmental effects of trichloroethylene (TCE) exposure on disease symptom onset (e.g., autoantibody production and proteinuria), lymphocyte proliferation, splenic B-cell populations, and thymic and splenic T-cell populations. MRL +/+ mice were exposed to TCE (0, 1,400 or 14,000 ppb) via drinking water beginning on gestation day (GD) 0 and continuing until 12 months of age. With the exception of splenic CD4-/CD8-cells in female mice only, no alterations were observed in splenic T-cell populations, numbers of splenic B220+ cells, or in lymphocyte proliferation at 12 months of age. Furthermore, populations of all thymic T-cell subpopulations were decreased in male but not female mice following exposure to 14,000 ppb TCE. Autoantibody levels (anti-dsDNA and anti-GA) were assessed periodically from 4 to 12 months of age. Over this period, no increase in autoantibody levels as compared to control was detected, suggesting that TCE did not contribute to or accelerate the development of autoimmune disease markers following lifetime exposure. Not only does this study offer encouraging results, but it is the first study to approach the development of autoimmunity in a novel lifetime exposure paradigm, using an autoimmune prone model, at environmentally relevant exposure levels.

Suppression of humoral immunity in mice following exposure to perfluorooctane sulfonate.

Adult male and female B6C3F1 mice were exposed to perfluorooctane sulfonate (PFOS) daily via gavage for 28 days (0, 0.005, 0.05, 0.1, 0.5, 1, or 5 mg/kg total administered dose [TAD]). Following exposure, various immune parameters were assessed and serum PFOS concentrations were determined. Lymphocyte proliferation was not altered in either gender. Natural killer cell activity was increased compared with control at 0.5, 1, and 5 mg/kg TAD in male mice but was not altered in female mice. At these treatment levels, splenic T-cell immunophenotypes were minimally altered in females, but all T-cell subpopulations were significantly modulated in males beginning at 0.1 mg/kg TAD. The sheep red blood cell (SRBC) plaque-forming cell (PFC) response was suppressed in male mice beginning at 0.05 mg/kg TAD and in females at 0.5 mg/kg TAD. Serum trinitrophenyl (TNP)-specific IgM titers were also decreased by PFOS after TNP-LPS (TNP conjugated to lipopolysacharide) challenge suggesting that the humoral immune effects may be attributed to the B-cell rather than T-cell because both T-dependent (SRBC) and T-independent (TI) (TNP-LPS) antigens result in suppressed IgM production. Based on the PFC response, the low observed effect level (LOEL) for males was 0.05 mg/kg TAD (ED(50) = 0.021 mg/kg TAD) and for females was 0.5 mg/kg TAD (ED(50) = 0.59 mg/kg TAD). Measured PFOS serum concentrations at these dose levels were 91.5 +/- 22.2 ng/g and 666 +/- 108 ng/g (mean +/- SD), respectively. The male LOEL serum level was approximately 14-fold lower than reported mean blood levels from occupationally exposed humans and fell in the upper range of concentrations reported for the general population. Overall, this study provides a profile of PFOS immunotoxicity showing effects at levels reported in humans and identifies the B-cells as a potential target.

Gestational exposure to perfluorooctane sulfonate suppresses immune function in B6C3F1 mice.

Perfluorinated alkyl acids (PFAAs) are used in a multitude of applications and are categorized as high-production volume chemicals produced in quantities exceeding 10,000 lbs/year. As a result, widespread exposure has been documented in adults, children, and infants. It is generally accepted that children are more sensitive to the effects of xenobiotic exposures during fetal and postnatal periods of development; therefore, considerable efforts are required to investigate the potential impact of a model PFAA, perfluorooctane sulfonate (PFOS) on children's immunological health. Using the pairing of female C57BL/6N mice with male C3H/HeJ, developmental immunotoxicity was evaluated in B6C3F1 pups following oral maternal exposure to PFOS on gestations days 1-17. Exposure levels included 0.1, 1, and 5 mg/kg/day PFOS. Natural killer (NK) cell activity, SRBC IgM plaque assay, CD4/8 lymphocytic subpopulations, nitrite production in peritoneal macrophages, and body/organ weights were evaluated at 4 and 8 weeks of age in F1 pups. No significant dose-responsive changes in maternal or pup body weights, flow cytometry, or macrophage function were observed, yet hepatomegaly was indicated in F1 male pups at 4 weeks of age. Functional deficits were not evident until 8 weeks of age when NK cell function and IgM production were significantly decreased. When compared with females, male pups were more sensitive to the effects of PFOS thereby establishing a no observed adverse effect level and low observed adverse effect level of 0.1 and 1.0 mg/kg/day (males only) following maternal PFOS exposure level, respectively. This study establishes that the developing immune system is sensitive to the effects of PFOS and results in functional deficits in innate and humoral immunity detectable at adulthood.

Suppression of humoral immunity following exposure to the perfluorinated insecticide sulfluramid.

Perfluorinated hydrocarbons have been manufactured for over 40 yr and have numerous applications in industry. This group of compounds has recently generated much interest, as some of these compounds such as perfluorooctane sulfonate (PFOS) and perfluoroctanic acid (PFOA) are persistent in the environment and detectable in blood samples of both wildlife and humans. Studies show that these perfluorinated compounds induce peroxisomal proliferation, induce hepatomegaly, alter steroidogenesis, and decrease body weight, accompanied by a wasting syndrome; however, effects on immune function have not been addressed at length. This study examined sulfluramid, a perfluorinated pesticide that is currently available in the marketplace and is a representative member of this class of chemicals. Adult female B6C3F1 mice were exposed via gavage to either an oil carrier control or sulfluramid for 14 d (1, 3, 10, or 30 mg/kg/d) or 28 d (0.3, 1, 3, or 10 mg/kg/d). Although responses were normal in natural killer cell activity and lymphocyte proliferation, dose-responsive suppression was noted in the plaque forming cell (PFC) response at exposure levels as low as 3 mg/kg/d in the 14-d exposure and 0.3 mg/kg/d for 28 d. Dose-responsive increases in liver mass were observed following treatment with 1, 3, 10, or 30 mg/kg/d for 14 d and 0.3, 1, 3, or 10 mg/kg/d for 28 d. A significant reduction in body weight was observed at the highest dose level in each study. Novel findings in this study indicate that sulfluramid suppresses immunoglobulin (Ig) M production. Additional immunotoxicity studies are required to understand potential mechanisms of suppression and determine potential health risks associated with exposure to perfluorinated hydrocarbons.

Developmental immunotoxicity of trichloroethylene (TCE): studies in B6C3F1 mice.

This study assessed the developmental immunotoxicity of trichloroethylene (TCE) in B6C3F1 mice exposed via drinking water (0, 1,400, 14,000 ppb) from gestation day 0 (GD0) to either 3 or 8 weeks of age. Lymphocyte proliferation, NK cell activity, SRBC-specific IgM production (PFC response), splenic B220+ cells, and thymic and splenic T-cell immunophenotypes were assessed at 3 and 8 weeks of age. Delayed type hypersensitivity (DTH) and autoantibodies to ds-DNA were assessed in 8-week old animals only. Proliferation and NK cell activity were not affected at either age. Decreased PFC responses were noted in male offspring at both ages and both TCE treatment levels. PFC responses in female offspring were suppressed by treatment with 14,000 ppb TCE at both ages assessed and at 1,400 ppb TCE at 8 weeks of age. Splenic numbers of B220 cells were only decreased in 3-week old pups exposed to 14,000 ppb TCE. The most pronounced alteration in T-cell subpopulations were increases in all thymic (CD4+, CD8+, CD4+/CD8+, and CD4-/CD8-) T-cell types in 8-week old animals. DTH was increased in females at both TCE levels and in males at the high dose only. These results indicate that TCE may be an effective developmental immunotoxicant and suggests that additional studies are required to determine the health risks associated with developmental exposure to TCE.