Linking Immunotoxicity and Ecotoxicological Effects at Higher Biological Levels - Ecological Biomarkers: Indicators of Ecotoxicological Effects - page 146

Regarding the extreme complexity of the immune response, immunological risk assess-
ment should include several immunomarkers, ideally covering the different arms of the
immune response. Differential cell count and phenotyping, histology, cytotoxic activity of
NK cells, and phagocytosis allow a relatively rapid detection of an impact on the immune
system. Other immunomarkers such as delayed-type hypersensitivity or T cell activation
address the mechanisms of immunotoxicity in more detail. In the future, efforts should
also be made to integrate challenges with pathogens in the immunological risk analysis.
Again, this should include a standardized process with reference pathogens.
In conclusion, since the emergence of this new discipline, immunotoxicology studies
have revealed that the immune system is highly sensitive to xenobiotics. Therefore, the
integration of immunomarkers into risk assessment analysis appears very promising.
Although immunomarkers cannot be used to causally identify the source of an immuno-
toxic effect, they do indicate an impairment of the immune response, enabling us to iden-
tify populations at risk. It is also important to recognize that impairment of the immune
system can be latent. Without an appropriate immunological survey, a weakened immune
competence will remain undetected until the population is challenged by a pathogen,
actually contributing to the severity of the epidemic. As illustrated by the still open ques-
tion of the contribution of potential immunotoxic effects induced by chemicals on the
severity of morbillivirus epizootics in marine mammals inhabiting heavily polluted areas,
a clear link between environmental exposure to pollutants and an increased sensitivity to
pathogens and cancer will remain very difficult to establish. However, immunotoxicology
significantly contributes to the gathering of a body of evidence leading to a more precise
definition of the risk associated with exposure to xenobiotics.
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