Linking Immunotoxicity and Ecotoxicological Effects at Higher Biological Levels - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 131

6
Linking Immunotoxicity and Ecotoxicological
Effects at Higher Biological Levels
Pauline Brousseau, Stéphane Pillet, Héloïse Frouin,
Michel Auffret, François Gagné, and Michel Fournier
CONTENTS
6.1 General Overview .............................................................................................................. 131
6.2 Case of Invertebrates—Bivalves ...................................................................................... 133
6.2.1 Introduction ............................................................................................................ 133
6.2.2 Hemocytes, Front Line of Immunocompetence ................................................ 134
6.2.3 Phagocytosis, Marker of Effect ............................................................................ 134
6.2.4 Oxidative Burst and Lysozymes .......................................................................... 135
6.2.5 Comparison between Markers and Adverse Effects ........................................ 136
6.2.6 Conclusions ............................................................................................................. 137
6.3 Case of Marine Mammals ................................................................................................ 138
6.3.1 Exposure of Marine Mammals to PTSs .............................................................. 138
6.3.2 Immunotoxicity of PTSs in Marine Mammals .................................................. 139
6.3.3 Immunotoxic Effects of Environmental Pollutants in Marine Mammals ..... 140
6.3.4 Environmental Contaminants and Health Risks in Marine Mammals ........ 142
6.4 Meaningfulness of Immune Biomarkers in Relation to Individual and
Population Health .............................................................................................................. 144
References ..................................................................................................................................... 146
6.1 General Overview
The function of the immune system is to fend off invasions by foreign pathogens and to
prevent the growth of malignant cells by a variety of effector cells, molecules, and chemi-
cal messengers that together compose a highly sophisticated system. Consequently, com-
plex interactions between the various components (cells, receptors, soluble factors) must
occur in order to provide well-orchestrated immune defenses. Protection against foreign
materials occurs through two different components of the immune system: the first,
described as immediate, produces a nonspecific response identified as innate immunity.
The second, described as long term, produces a specific response as well as an immuno-
logical memory identified as acquired immunity. This immunological memory is a key
element, which favors induction of a rapid specific response in the case of repeated assaults
by the same foreign material. In regard to aquatic species, the immune system of teleosts
has a high degree of similarity with that of mammals. Based on evolutionary advances
and specificity, the complexity of the immune system is less in lower vertebrates and in
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