Effects of Heavy Metals on Immunocompetence of White-Footed Mice (Peromyscus Leucopus)

Abstract

Continued human population growth and industrialization result in increased contamination of wildlife habitats. Effects of such habitat deterioration on the well-being of natural populations are unclear. Exposure to contaminants may impair immunocompetence, thereby increasing disease susceptibility. The mammalian immune system is important in maintaining health and in its sensitivity to toxins. In our study conducted from May 1999 through May 2001, we examined assays of immunocompetence in the white-footed mouse (Peromyscus leucopus) that inhabited reference sites and sites significantly contaminated with mixtures of heavy metals. We estimated potential exposure and uptake of heavy metals by measuring the level of each contaminant in representative soil and tissue samples. Intraindividual variation across mice, but not sex, explained a large portion of the overall variance in immune response, and spleen weight was significantly affected by mouse age. We found no evidence that residence on contaminated sites had any effect on immunopathology and humoral immunity as measured in our study. We suggest that field and laboratory studies in ecotoxicology provide estimates of exposure to contaminants (i.e., tissue analyses) to establish a database suitable to clarify the dose-response relationship between contaminants and target systems.

Parasites in the City: Degree of Urbanization Predicts Poxvirus and Coccidian Infections in House Finches (Haemorhous mexicanus)

“…Pollutants (e.g. organochlorines, trace metals) may also negatively affect immune responses of urban animals [66] [67] [68] [69] [70] [71]. Interestingly, in a recent study of urban and rural house sparrows ( Passer domesticus ), feather lead concentration was associated with the degree of infection by one species of avian malaria ( Plasmodium relictum ) [14].…”

Urbanization, Trace Metal Pollution, and Malaria Prevalence in the House Sparrow

“…Although studies on possible effects of pollutants on immune system function remain limited in birds [22], [23], toxicants are know to interfere with immune receptor binding and trigger inappropriate and inhibited immune responses in model species [24]–[28].…”

Exposure to residual concentrations of elements from a remediated coal fly ash spill does not adversely influence stress and immune responses of nestling tree swallows

“…Exposure to elevated concentrations of Pb or a mixture of elements including As, Cd, Cu, Pb, Hg, Se and Zn was associated with reduced humoral immunity [zebra finch ( Taeniopygia guttata ) and great tit ( Parus major ), Snoeijs et al , 2004 , 2005], while cell-mediated immunity can be impaired by exposure to Hg in tree swallows ( Tachycineta bicolor , Hawley et al , 2009 ). However, other studies have detected no effect of these same elements on humoral ( Wayland et al , 2003 ; Biser et al , 2004 ; Hawley et al , 2009 ) or cell-mediated immunity ( Snoeijs et al , 2005 ; Baos et al , 2006b ), and a few studies have even detected stimulatory effects of Se exposure on these immune responses ( Wayland et al , 2002 ; Surai, 2006 ; Brady et al , 2013 ). Robust innate and cell-mediated immune responses require adequate dietary concentrations of Cu, Fe, Se and Zn (reviewed by Maggini et al , 2007 ; Wintergerst et al , 2007 ), and it is possible that moderate increases in these elements, below levels associated with toxic effects, are responsible for the enhanced immune responses detected in some studies.…”