Trans-generational and neonatal humoral immune responses in West Greenland sledge dogs (Canis familiaris) exposed to organohalogenated environmental contaminants.

Previous investigations in the Arctic have suggested OHC (organohalogen contaminant) induced immune toxic effects on e.g. polar bears (Ursus maritimus). We therefore studied the dietary impact from minke whale blubber (Balaenoptera acutorostrata), rich in polyunsaturated fatty acids and OHCs, on the humoral immunity of 7 captive West Greenland sledge dog (Canis familiaris) bitches and their 4 pups constituting a sentinel model species for polar bears. A control group was composed of 8 bitches and their 5 pups all fed pork (Suis scrofa) fat. The study included serum IgG measurements (bitches and pups) and specific immune responses towards tetanus toxoid (bitches) and diphtheria toxoid (pups) as well as influenza virus (pups). The analyses showed that IgG concentrations were non-significantly lowest in exposed bitches and pups (t-test: all p>0.05). In addition, significant lower antibody response was detected in exposed pups immunized with influenza virus at age 3 months (t-test: both p<0.05). No clear group differences were found for tetanus toxoid in bitches and diphtheria toxoid in pups. The results suggest that the humoral immune system of sledge dogs may be suppressed by the dietary blubber composition of OHCs and polyunsaturated fatty acids while a larger follow-up study is recommended in order to investigate this relationship further.

The toxic effects of multiple persistent organic pollutant exposures on the post-hatch immunity maturation of glaucous gulls.

This study tested whether the immune system of the glaucous gull (Larus hyperboreus) chicks became affected by existing environmental contaminants. An experimental group was given food that mimicked the natural contaminant mixture found in food from the North Atlantic marine environment, while the control group was given the equivalent of nearly clean food. All chicks were immunized with herpes virus (EHV), reovirus (REO), influenza virus (EIV), and tetanus toxoid (TET) in order to test their ability to respond to foreign specific antigens. At 8 wk, the experimental group had 3- to 13-fold higher concentrations of hexachlorobenzene (HCB), oxychlordane, p,p'-DDE, and total polychlorinated biphenyls (Sigma PCB) than did the control. The experimental group produced significantly lower antibody titer against EIV and had lower concentrations of immunoglobulin-G (IgG) and -M (IgM) in blood. Hematocrit percent and leukocyte numbers did not differ between the two groups. The ability of lymphocytes to proliferate in vitro was tested with three mitogens, phytohemagglutinin (PHA), concanavalin A (Con A), and pokeweed mitogen (PWM), and three antigens, keyhole limpet hemocyanin (KLH), TET, and Mycobacterium avium subsp. paratuberculosis tuberculin purified protein derivative (PPD). The experimental group had a significantly higher peripheral blood lymphocyte response to PHA and to spleen lymphocytes in vitro stimulated with Con A and PCB congeners 99 or 153, while the Con A, PWM, KLH, TET, PPD, and Con A plus PCB-156 or -126 showed nonsignificant differences between groups. Data indicate that the combined effect of multiple persistent organic pollution exposures occurring naturally in the Arctic negatively affect the immune system of the glaucous gull chick.

Immunotoxicity of polychlorinated biphenyls (PCB) in free-ranging gray seal pups with special emphasis on dioxin-like congeners.

Increased pinniped and dolphin mortality rates have led to speculations that persistent pollutants, in particular polychlorinated biphenyls (PCB), are immunomodulatory, making individuals susceptible to infections. The aim of the present study was to investigate effects that PCB may exert on peripheral blood mitogen-induced lymphocyte proliferation responses in free-ranging gray seal (Halichoerus grypus) pups from the polluted Baltic Sea and from the cleaner open waters of the Atlantic Ocean. T-cell mitogen (phytohemagglutinin [PHA] and concanavalin A [Con A]) and T-/B-cell mitogen (pokeweed mitogen [PWM]) responses were significantly lower in the more PCB-contaminated Baltic gray seal pups than in reference pups from the Atlantic. Best regression analysis revealed that dioxin-like mono-ortho PCB accounted for the immunosuppressive responses. In the Baltic seals, the immunosuppressive effects were limited to the more persistent dioxin-like mono-ortho PCB. In the Atlantic seals a positive correlation existed between PCB concentrations and mitogen-induced lymphocyte proliferation responses. Although direct cause-effect relationships are difficult to demonstrate in free-ranging animals, our results are consistent with the weight of evidence available that PCB, and dioxin-like PCB in particular, modulate lymphocyte function in free-ranging marine mammals. Thus, exposure to PCB most likely result in increased susceptibility to infections or reduced host resistance in pinnipeds.

An assessment of the toxicological significance of anthropogenic contaminants in Canadian arctic wildlife.

Anthropogenic contaminants have been a concern in the Canadian arctic for over 30 years due to relatively high concentrations of bioaccumulating and biomagnifying organochlorine contaminants (OCs) and toxic metals found in some arctic biota and humans. However, few studies have addressed the potential effects of these contaminants in Canadian arctic wildlife. Prior to 1997, biological effects data were minimal and insufficient at any level of biological organization. The present review summarizes recent studies on biological effects related to contaminant exposure, and compares new tissue concentration data to threshold effects levels. Weak relationships between cadmium, mercury and selenium burdens and health biomarkers in common eider ducks (Somateria mollissima borealis) in Nunavut were found but it was concluded that metals were not influencing the health of these birds. Black guillemots (Cepphus grylle) examined near PCB-contaminated Saglek Bay, Labrador, had enlarged livers, elevated EROD and liver lipid levels and reduced retinol (vitamin A) and retinyl palmitate levels, which correlated to PCB levels in the birds. Circulating levels of thyroid hormones in polar bears (Ursus maritimus) were correlated to PCB and HO-PCB plasma concentrations, but the impact at the population level is unknown. High PCB and organochlorine pesticide concentrations were found to be strongly associated with impaired humoral and cell-mediated immune responses in polar bears, implying an increased infection risk that could impact the population. In beluga whale (Delphinapterus leucas), cytochromes P450 (phase I) and conjugating (phase II) enzymes have been extensively profiled (immunochemically and catalytically) in liver, demonstrating the importance of contaminants in relation to enzyme induction, metabolism and potential contaminant bioactivation and fate. Concentrations of OCs and metals in arctic terrestrial wildlife, fish and seabirds are generally below effects thresholds, with the possible exception of PCBs in burbot (Lota lota) in some Yukon lakes, Greenland shark (Somniosus microcephalus), glaucous and great black-backed gulls (Larus hyperboreus and L. marinus), and TEQs of dioxin-like chemicals in seabird eggs. PCB and DDT concentrations in several arctic marine mammal species exceed effects thresholds, although evidence of stress in these populations is lacking. There is little evidence that contaminants are having widespread effects on the health of Canadian arctic organisms, with the possible exception of polar bears. However, further research and better understanding of organohalogen exposure in arctic biota is needed considering factors such as tissue levels that exceed effects thresholds, exposure to "new" organohalogen contaminants of concern, contaminated regions, and climate change.

Does high organochlorine (OC) exposure impair the resistance to infection in polar bears (Ursus maritimus)? Part II: Possible effect of OCs on mitogen- and antigen-induced lymphocyte proliferation.

Previous studies have reported alarmingly high levels of organochlorines (OCs), particularly polychlorinated biphenyls (PCBs), in free-ranging polar bears (Ursus maritimus). In this study plasma concentration of PCBs ranged from 14.8 to 200 ng/g wet weight. The aim of the study was to investigate associations between OCs and lymphocyte proliferation after in vitro stimulation with different mitogens and antigens. In 1998 and 1999, 26 and 30 free-ranging polar bears from Svalbard and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated tetanus toxoid and hemocyanin from keyhole limpets (KLH) to sensitize lymphocytes. At recapture, blood was sampled for determination of plasma levels of PCBs and organochlorine pesticides (OCPs) and lymphocyte proliferation after in vitro stimulation with specific mitogens--phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (Con A), lipopolysaccharide (LPS), and purified protein derivative of Mycobacterium avium subsp. paratuberculosis (PPD)--and antigens: tetanus toxoid and KLH. The combinations of sum(PCBs) (sum of 12 individual PCB congeners), sum(OCPs) (sum of 6 OCPs), and their interactions contributed up to 15% of the variations in the lymphocyte responses. By using multiple regression analyses, followed by classical mathematic function analyses, thresholds for immunomodulation were estimated. Depending on the lymphocyte proliferation response studied, the estimated thresholds for significant immunomodulation were within the concentration ranges 32-89 ng/g wet weight (ww) and 7.8-14 ng/g ww for sum(PCBs) and sum(OCPs), respectively. Thus, this study demonstrated that OC exposure significantly influences specific lymphocyte proliferation responses and part of the cell-mediated immunity, which also is associated with impaired ability to produce antibodies (Lie et al., 2004).

Does high organochlorine (OC) exposure impair the resistance to infection in polar bears (Ursus maritimus)? Part I: Effect of OCs on the humoral immunity.

This study was undertaken to assess if high levels of organochlorines (OCs) are associated with decreased ability to produce antibodies in free-ranging polar bears (Ursus maritimus) and thus affect the humoral immunity. In 1998 and 1999, 26 and 30 polar bears from Svalbard, Norway, and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated influenza virus, reovirus, and herpes virus and tetanus toxoid. Blood was sampled at immunization and at recapture for determination of plasma levels of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), serum immunoglobulin G (IgG) concentrations, and specific antibodies against influenza virus, reovirus, and herpes virus, tetanus toxoid, and Mannheimia haemolytica. The OCs alone contributed with up to 7% to the variations in the immunological parameters. The combination of sigma PCBs (sum of 12 individual PCB congeners), sigma OCPs (sum of 6 OCPs), and biological factors accounted for 40-60% of the variation in the immunological parameters. Negative associations were found between sigma PCBs and serum immunoglobulin G (IgG) levels and between sigma PCBs and increased antibody titers against influenza virus and reovirus following immunization. In contrast, a positive association was registered between sigma PCBs and increased antibodies against tetanus toxoid. sigma OCPs also contributed significantly to the variations in the immunological responses. OCs did not have the same impact on the antibody production against M. haemolytica. The present study demonstrated that high OC levels may impair the polar bears ability to produce antibodies and thus may produce impaired resistance to infections.

The effects of the Penicillium mycotoxins citrinin, cyclopiazonic acid, ochratoxin A, patulin, penicillic acid, and roquefortine C on in vitro proliferation of porcine lymphocytes.

The in vitro effect of each of the Penicillium mycotoxins citrinin (CIT), cyclopiazonic acid (CPA), ochratoxin A (OTA), patulin (PAT), penicillic acid (PIA) and roquefortine C (RQC) on mitogen induced lymphocyte proliferation was determined using purified lymphocytes from 6 piglets. Dose response curves for each mycotoxin were generated and the concentrations producing 50% inhibition of cell proliferation (IC(50)) were estimated. OTA and PAT were the most potent toxins with IC(50) of 1.3 and 1.2 micromol/l, respectively (0.52 and 0.18 mg/l, respectively). Based on molar concentrations, OTA was 15, 30, 40, and 65 times more potent as an inhibitor than PIA, CIT, CPA and RQC, respectively.

Combined effects of selected Penicillium mycotoxins on in vitro proliferation of porcine lymphocytes.

The in vitro effect of combinations of the Penicillium mycotoxins citrinin (CIT), cyclopiazonic acid (CPA), ochratoxin A (OTA), patulin (PAT), penicillic acid (PIA) and roquefortine C (RQC) on mitogen induced lymphocyte proliferation was determined using purified lymphocytes from six piglets. Dose-response curves for each mycotoxin and mycotoxin combinations were generated. The combined effects of toxin pairs based on IC20 were illustrated in isobole diagrams and statistically calculated. OTA and CIT elicited a synergistic effect. Four toxin pairs elicited additive effects, four pairs less-than-additive effects and six pairs independent effects. Thus, the majority of toxin pairs tested produced lower combined effects than an additive effect. The results indicate that the sum effect of all toxins is less than that from the summation of concentrations of the individual compounds, adjusted for differences in potencies.