Effects of Organochlorine Contaminants on Loggerhead Sea Turtle Immunity: Comparison of a Correlative Field Study andIn VitroExposure Experiments

Abstract

Several laboratory and field studies indicate that organochlorine contaminants (OCs), such as poly-chlorinated biphenyls (PCBs) and pesticides, modulate immune responses in rodents, wildlife, and humans. In the present study we examined the effects of OCs on immunity in free-ranging loggerhead sea turtles (Caretta caretta). Mitogen-induced lymphocyte proliferation responses, lysozyme activity, and OC concentrations were measured from blood samples. Mitogens chosen in the lymphocyte proliferation assay were phytohemagglutinin (PHA) and concanavalin A (ConA) for T-lymphocyte stimulation, and lipopolysaccharide (LPS) and phorbol 12,13-dibutyrate (PDB) for B-lymphocyte stimulation. Lysozyme activity was significantly and negatively correlated with whole-blood concentrations of 4,4′-dichlorodiphenyldichloroethylene (4,4′-DDE) and the sum of chlordanes. Lymphocyte proliferation responses stimulated by PHA, LPS, and PDB were significantly and positively correlated with concentrations of the sum of PCBs measured in whole blood. LPS- and PDB-induced proliferation were also significantly and positively correlated with 4,4′-DDE blood concentrations. These correlative observations in free-ranging turtles suggest that current, chronic exposure to OCs may suppress innate immunity and enhance certain lymphocyte functions of loggerhead sea turtles. To further test this hypothesis, lymphocyte proliferation was measured after in vitro exposure of peripheral blood leukocytes from 16 turtles to Aroclor 1254 (0–13.5 μg/mL) or 4,4′-DDE (0–13.4 μg/mL). Both contaminants increased PHA- and PDB-induced proliferation at concentrations below those that affected cell viability. Moreover, the concentrations that enhanced PDB-induced proliferation in vitro were similar to concentrations measured in turtles with the highest proliferative responses. The similarities between the in vitro experiments and the correlative field study suggest that OC exposure modulates immunity in loggerhead turtles.

Complex Interplay of Body Condition, Life History, and Prevailing Environment Shapes Immune Defenses of Garter Snakes in the Wild

“…Our results contrast with those of previous studies that have measured in vitro lymphocyte proliferation responses in reptiles. While studies in another snake species found higher immune responses in females (Saad and Shoukrey 1988;Saad 1989), two studies in turtles reported no sex differences (Muñoz and De la Fuente 2001b; Keller et al 2006). On the other hand, the lack of sex differences in innate immunity parallels findings in water pythons (Ujvari and Madsen 2011) and marine iguanas (French et al 2010).…”

Kemp's Ridley Sea Turtle Saga and Setback: Novel Analyses of Cumulative Hatchlings Released and Time-Lagged Annual Nests in Tamaulipas, Mexico

“…Continuous low-level exposure to oil in the form of tar balls, slicks, or elevated background concentrations also challenge animals facing other natural and anthropogenic stresses. Types of trauma can include skin irritation, altering of the immune system, reproductive or developmental damage, and liver disease (Keller et al 2004;Keller et al 2006). Chronic exposure may not be lethal by itself, but it may impair a turtle's overall fitness so that it is less able to withstand other stressors .…”

Stereoselective metabolism, distribution, and bioaccumulation brof triadimefon and triadimenol in lizards

“…Past attention was focused on measuring body burdens of various pollutants to wild reptiles which gave an understanding of historical exposure of given populations (Buono et al, 2007;Holem et al, 2008;Mann et al, 2007;Moss et al, 2009;Trinchella et al, 2006;De Falco et al, 2007;Keller et al, 2006;Simoniello et al, 2010;van de Merwe et al, 2010). However, the population-level effects and actual risks of pollutants on reptiles are still generally understudied (Weir et al, 2010).…”