MP12 Organic, Metallic, Organometallic Pollutants
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(GRA-1117-835508) Lymphocyte proliferation in adult and prefledgling herring gulls exposed to environmental contaminants in the Great Lakes.

Ramanunni, A¹, Grasman, K¹, Fox, G², ¹ Wright State university, Fairborn, Ohio, U.S.A² Canadian Wildlife Service, Ottawa, Ontario, Canada

ABSTRACT- Developmental and chronic exposure to organochlorine contaminants has been associated with suppression of T cell-mediated immune responses in fish-eating birds such as gulls and terns. Organochlorines can increase or decrease lymphocyte proliferation in laboratory studies. The objective of this study was to assess lymphocyte proliferation in Great Lakes herring gulls (Larus argentatus) exposed to organochlorines. Blood samples were collected during 2003 from adult and prefledgling herring gulls from Chantry Island (C) (reference site) and Saginaw Bay (SB) in Lake Huron, and Hamilton Harbor (HH) and Scotch Bonnet Island (S) in Lake Ontario. Adult birds were trapped during mid-incubation. Herring gull chicks were sampled at 3 and 4 weeks after hatch. Lymphocytes were isolated by slow spin centrifugation and cryopreserved. After thawing, lymphocytes were cultured with T-cell (ConA, PHA + PMA) and B-cell (LPS) mitogens for 48 hours. Proliferation was measured by ELISA using 5-Bromo-2′-deoxy-uridine incorporation assay and expressed in terms of stimulation index: mean optical density in mitogen-stimulated wells divided by mean optical density in non-stimulated wells. Lymphocyte samples had good viability post thaw (mean=80%) and showed strong proliferation in response to mitogens. In adults, T-cell proliferation was increased at SB compared to C (30% for PHA+PMA; 60% for Con A), and B-cell proliferation was decreased 40% at SB and 32% at HH. In 3 week old chicks, Con A-induced proliferation was increased 50% at HH. At SB proliferation with PHA+PMA was increased 25%, and at S B-cell proliferation was increased 65%. Four week old chicks showed significant proliferation but no significant intersite differences. This study demonstrated that mitogen-induced proliferation assays using cryopreserved lymphocytes are useful indicators for assessing immune function in wild birds. The differences in proliferation in Great Lakes herring gulls from different sites may be associated with environmental contaminants.

Key words: Lymphocyte proliferation, organochlorines, Herring gulls