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Perfluoroalkyl acids (PFAAs) are highly stable compounds that have been associated with immunotoxicity in epidemiologic studies and experimental rodent models. Lengthy half-lives and resistance to environmental degradation result in bioaccumulation of PFAAs in humans and wildlife. Perfluorooctane sulfonate (PFOS), the most prevalent PFAA detected within the environment, is found at high levels in occupationally exposed humans. We have monitored the environmental exposure of dolphins in the Charleston, SC region for over 10 years and levels of PFAAs, and PFOS in particular, were significantly elevated. As dolphins may serve as large mammal sentinels to identify the impact of environmental chemical exposure on human disease, we sought to assess the effect of environmental PFAAs on the cellular immune system in highly exposed dolphins. Herein, we utilized a novel flow cytometry-based assay to examine T cell-specific responses to environmental PFAA exposure ex vivo and to exogenous PFOS exposure in vitro. Baseline PFOS concentrations were associated with significantly increased CD4 + and CD8 + T cell proliferation from a heterogeneous resident dolphin population. Further analysis demonstrated that in vitro exposure to environmentally relevant levels of PFOS promoted proinflammatory cytokine production and proliferation in a dose-dependent manner. Collectively, these findings indicate that PFOS is capable of inducing proinflammatory interferon-gamma, but not immunoregulatory interleukin-4 production in T cells, which may establish a state of chronic immune activation known to be associated with susceptibility to disease. These findings suggest that PFOS directly dysregulates the dolphin cellular immune system and has implications for health hazards. Copyright © 2017 John Wiley & Sons, Ltd., (Copyright © 2017 John Wiley & Sons, Ltd.)

The Deepwater Horizon oil spill was one of the worst environmental disasters on record in the United States. Response efforts to reduce the magnitude of the oil slick included the use of thousands of gallons of the chemical dispersant Corexit™ in surface and deep-water environments. The immunotoxicity of Louisiana sweet crude oil and the chemical dispersant Corexit was examined using lymphocyte proliferation (LP) and natural killer cell (NK) assays as measures of impact on the adaptive (LP) and innate (NK) immune response in bottlenose dolphins. Study results show that both high-energy media-accommodated fractions (MAF) and chemically enhanced MAF (CEMAF) mixtures modulate immune function. Following exposure to Louisiana sweet crude, both B- and T-cell proliferation of white blood cells was increased for all exposure concentrations, compared to control; however, this increase was only significant for the 50% and 100% treatments. In contrast, exposure of white blood cells to the CEMAF mixture significantly decreased both T- and B-cell proliferation in the 25%, 50% and 100% treatments. NK cell activity was enhanced significantly by CEMAF mixtures for the 50% and 100% treatments. The immunosuppression of LP at environmentally relevant concentrations of oil and dispersant suggests that marine mammals may be unable to mount an adequate defense against xenobiotic threats following exposure to oil and dispersant, leaving them more susceptible to disease. In contrast, NK cell activity was significantly enhanced, which may increase an organism's tumor or viral surveillance ability by mounting an enhanced immune response. Copyright © 2016 John Wiley & Sons, Ltd., (Copyright © 2016 John Wiley & Sons, Ltd.)

Polybrominated diphenyl ethers (PBDEs) are an emerging contaminant of concern with low level exposures demonstrating toxicity in laboratory animals and wildlife, although immunotoxicity studies have been limited. Bottlenose dolphin peripheral blood leukocytes (PBLs) and mouse splenocytes were exposed to environmentally relevant DE-71 (a penta-PBDE mixture) concentrations (0-50 µg ml(-1) ) in vitro. Natural killer (NK) cell activity and lymphocyte (B and T cell) proliferation were evaluated using the parallelogram approach for risk assessment. This study aimed to substantiate results from field studies with dolphins, assess the sensitivities between the mouse model and dolphins, and to evaluate risk using the parallelogram approach. In mouse cells, NK cell activity increased at in vitro doses 0.05, 0.5 and 25 µg DE-71 ml(-1) , whereas proliferation was not modulated. In dolphin cells, NK cell activity and lymphocyte proliferation was not altered after in vitro exposure. In vitro exposure of dolphin PBLs to DE-71 showed similar results to correlative field studies; NK cell activity in mice was more sensitive to in vitro exposure than dolphins, and the parallelogram approach showed correlation with all three endpoints to predict risk in bottlenose dolphins., (Copyright © 2014 John Wiley & Sons, Ltd.)

Previous studies in our lab have shown that perfluorooctane sulfonate (PFOS) modulates immune function in mice and correlates with many immune parameters in bottlenose dolphins (Tursiops truncatus). In this study, bottlenose dolphin peripheral blood leukocytes (PBLs) and adult female B6C3F1 mouse splenocytes were exposed to environmentally relevant PFOS concentrations (0-5 µg ml(-1)) in vitro; and natural killer (NK) cell activity and lymphocyte proliferation (T and B cell) were assessed using the parallelogram approach for risk assessment. The objectives were: to corroborate results from the correlative studies in bottlenose dolphins with in vitro PFOS exposures; to evaluate the sensitivity of the mouse model as compared with bottlenose dolphins; and to assess risk using the parallelogram approach. In mouse cells, NK cell activity was decreased at in vitro doses of 0.01, 0.5, 0.1, 0.5 and 1 µg PFOS ml(-1) and increased at 5 µg ml(-1). Additionally, B cell proliferation was not altered, but T cell proliferation was decreased at all in vitro PFOS exposures. In dolphin cells, NK cell activity and T cell proliferation were not altered by in vitro PFOS exposure, but B cell proliferation exhibited a positive association in relation to PFOS dose. Overall, the data indicates that: the in vitro exposures of bottlenose dolphin PBLs exhibited results similar to reported correlative fields studies; that mice were generally more sensitive (for these selected endpoints) than were dolphins; and that the parallelogram approach could be used two-thirds of the time to predict the effects in bottlenose dolphins., (Copyright © 2013 John Wiley & Sons, Ltd.)