Contaminant-related suppression of delayed-type hypersensitivity and antibody responses in harbor seals fed herring from the Baltic Sea.

Abstract

Recent mass mortalities among several marine mammal populations have led to speculation about increased susceptibility to viral infections as a result of contaminant-induced immunosuppression. In a 2.5-year study, we fed herring from either the relatively uncontaminated Atlantic Ocean or the contaminated Baltic Sea to two groups of captive harbor seals and monitored immune function in the seals. Seals fed the contaminated fish were less able to mount a specific immunological response to ovalbumin, as measured by in vivo delayed-type hypersensitivity (DTH) reactions and antibody responses. The skin reaction to this protein antigen was characterized by the appearance of mononuclear cells which peaked at 24 hr after intradermal administration, characteristic of DTH reactions in other animals studied. These DTH responses correlated well with in vitro tests of T-lymphocyte function, implicating this cell type in the reaction. Aryl-hydrocarbon (Ah) receptor-dependent toxic equivalent (TEQ) profiles in blubber biopsies taken from the seals implicated polychlorinated biphenyls rather than dioxins or furans in the observed immunosuppression. Marine mammal populations currently inhabiting polluted coastal environments in Europe and North America may therefore have an increased susceptibility to infections, and pollution may have played a role in recent virus-induced mass mortalities.Imagesp162-aFigure 1.Figure 2. AFigure 2. BFigure 2. CFigure 3.Figure 4.

Organochlorine-Associated Immunosuppression in Prefledgling Caspian Terns and Herring Gulls from the Great Lakes: An Ecoepidemiological Study

“…Our findings are (34) consistent with the results of several marine mammal studies. Harbor seals fed HAHcontaminated herring from the Baltic Sea had reduced delayed-type hypersensitivity (T-cell-mediated) and reduced mitogeninduced proliferative T-cell responses (67,68). Mitogen-induced proliferative Tcell responses were inversely correlated with blood PCB and DDE concentrations in male bottlenose dolphins from the west SagB coast of Florida (69).…”

“…In herring gull eggs, gradiSagB ents in PCBs and DDE all occurred in the (15) same rank order. However, PCBs occurred at much higher concentrations than DDE, and suppression of T-cell-mediated (68), but mitogen-induced proliferation of B cells was not affected (10) (67). B-cell proliferation showed no associations with organochlorines in male bottlenose dolphins from the west coast of Florida (69).…”

“…Subsequent laboratory studies showed that HAHs increased susceptibility to bacteria (42,48,61), viruses (26,50,62), and protozoan parasites (26). Several investigators suggested associations between epizootics and elevated organochlorine exposure in beluga whales (Delphinapterus leucas) in the St. Lawrence Estuary (63), California sea lions (Zalophus californianus) on San Miguel Island (64,65), harbor seals (Phoca vitulina) in Europe (66)(67)(68), and bottlenose dolphins (Tursiops truncatus) in the Atlantic Ocean (69). At highly contaminated sites in the Great Lakes, doublecrested cormorants (Phalacrocorax auritus) had increased rates of eye infections associated with Pasteurella multocida (70).…”

Chronic Toxicity of Environmental Contaminants: Sentinels and Biomarkers

“…There was an inverse relationship between DTH swelling and total Ah receptorbinding contaminant levels. Furthermore, the serum antibody titers to ovalbumin were approximately 37% lower in the seals fed the contaminated herring than those fed the control herring (51). Earlier studies had shown that seals fed PCB-contaminated fish had significantly lower serum retinol levels, which when converted to vitamin A, can play an important role in resistance to microbial infections (52,53).…”

Short term fasting does not aggravate immunosuppression in harbour seals (Phoca vitulina) with high body burdens of organochlorines

“…reproductive toxicity (Helle et al 1976a;Helle et al 1976b;Reijnders, 1986), hormonal alterations (Brouwer et al 1989;Subramanian et al 1987), and immunotoxicity (De Swart et al 1994;De Swart et al 1995b;Ross et al 1995a;Ross et al 1995b). Recent morbillivirus related mass mortalities among marine mammals inhabiting polluted coastal waters De Swart et al 1995a) led to speculation about a possible contribution of environmental contaminant-induced immunosuppression to the severity and extent of these epizootics (Osterhaus and Vedder, 1989;Simmonds and Johnston, 1989).…”