Effects of in ovo exposure to PCBs 126 and 77 on mortality, deformities and post-hatch immune function in chickens.

In laboratory experiments, planar PCBs produce immune organ atrophy in chicken embryos. To study the immunotoxic effects of PCBs in birds, the coplanar congeners 3,3',4,4',5-pentachlorobiphenyl (PCB 126) and 3,3',4,4'-tetrachlorobiphenyl (PCB 77) were injected into the air cell of fertile white leghorn chicken eggs before incubation at doses of 0.25 and 0.5 ng/g egg PCB 126 and 0.64 ng/g egg PCB 77. Mortality and deformities were assessed during incubation of the eggs, and immune function was analyzed post-hatch using phytohemagglutinin (PHA) skin test for T-cell mediated immunity, antibody titers to sheep red blood cells (SRBC), mitogenesis of peripheral blood lymphocytes, and immune organ mass and cellularity. Exposure to 0.25 ng/g PCB 126 elevated mortality (61% and 69%) and deformities (31% and 32%), three or more times higher than controls. Two-fold suppression of antibody titers was observed in 28 day old chicks exposed to PCB 126 or PCB 77. No consistent alterations in PHA skin response or lymphocyte proliferation were observed. In 14 day old chicks in experiment two, PCB 126 decreased thymus and bursa cellularity by 33% and 35%, respectively. Immune organ atrophy was transient, recovering to control levels by 42 days of age. These experiments demonstrate that PCB 126 and 77 suppress antibody responses in juvenile chickens following an in ovo PCB exposure. Results reinforce the need for measuring multiple immune endpoints to detect immunotoxicity.

Effect of In Ovo exposure to an organochlorine mixture extracted from double crested cormorant eggs (Phalacrocorax auritus) and PCB 126 on immune function of juvenile chickens.

Organochlorine (OC) contaminants including polychlorinated biphenyls (PCBs) and p, p'-dichlorodiphenyldichloroethylene (DDE) have been associated with immune modulation in wild fish-eating birds from the Great Lakes. The objective of this study was to evaluate the immune function of juvenile chickens after in ovo exposure to PCB 126 or an environmentally relevant OC mixture extracted from eggs of double crested cormorants (Phalacrocorax auritus) from Green Bay, Lake Michigan, USA. Fertile white leghorn chicken (Gallus domesticus) eggs were injected before incubation with 0.55-1.79 ng TCDD equivalents (TEQ)/egg PCB 126 and 1.2-4.9 ng TEQs/egg of cormorant egg extract into the air cell in two separate experiments. After hatching, the immune function was tested using in vivo phytohemagglutinin (PHA) skin response in 11-day-old chicks, antibody titers to immunization with sheep red blood cells (SRBC) in 28-day-old chicks, and, at necropsy, thymus and bursal mass and cellularity. PCB 126 decreased antibody titers at all doses and decreased the thymus and bursa index but not cellularity at 1.79 ng TEQ/egg. The cormorant egg extract caused no significant alterations in immune function even though it has been demonstrated as immunotoxic in chicken embryos. However, twofold to threefold increases in total anti-SRBC titers in 28-day-old chicks exposed to 1.2 or 2.4 ng TEQ/egg of cormorant extract were similar to elevations in anti-SRBC titer observed in Caspian tern (Sterna caspia) chicks from a highly OC-contaminated site in Saginaw Bay, Lake Huron. Posthatch exposure to OC through fish consumption in addition to in ovo OC exposure might be associated with the immune modulation reported in wild birds. Chicks in this study might have begun to compensate for embryonic immunotoxicity by the ages at which we studied them.

Isolation, cryopreservation, and mitogenesis of peripheral blood lymphocytes from chickens (Gallus domesticus) and wild herring gulls (Larus argentatus).

Monitoring the toxicity of environmental contaminants on the physiologic function of wild birds often includes measures of immune function. The purpose of this study was to apply methods of isolation, cryopreservation, and cell culture of chicken lymphocytes to blood samples from herring gulls, which are a sentinel species for biomonitoring studies in the Great Lakes and northern North America. Slow-spin centrifugation and density gradient isolation of lymphocytes were compared using chicken blood. Significant thrombocyte contamination of density gradient isolated samples (40% to 77% thrombocytes) led to the use of slow-spin centrifugation (2% thrombocytes) for blood from herring gulls. Cryopreserved blood samples were collected from adult and prefledgling herring gulls at sites of low environmental contamination around the Great Lakes and the Bay of Fundy between 1999 and 2002. Cryopreservation decreased the viability of lymphocytes from wild birds, but a high proportion of samples yielded enough live lymphocytes to assess function in culture. Cryopreserved lymphocytes from herring gulls proliferated in response to phytohemagglutinin (PHA), concanavalin-A, phorbol myristate acetate (PMA), PHA plus PMA, and lipopolysaccharide stimulation. Weber and Roswell Park Memorial Institute medium (RPMI) 1640 media were compared for culture of lymphocytes. Weber medium better supported chicken B-lymphocyte proliferation than RPMI 1640 and supported chicken T-lymphocyte proliferation of a similar magnitude as RPMI. Proliferation responses for lymphocytes from prefledgling herring gulls were stronger in Weber medium than RPMI medium, especially for PHA, for which there was no stimulation in RPMI. Proliferation responses of lymphocytes from adult herring gulls were up to twofold greater than that for prefledgling herring gulls. The magnitudes of proliferation responses were similar to that for chicken lymphocytes. These methods have subsequently proven useful in ecotoxicology studies that involve species in remote locations.