The immune system of marine mammals.: Part 1:: Immune response, cytokines and immunotoxicity

The worldwide increasing incidence of infectious and neoplastic diseases in whales and dolphins leads to speculations about the possible negative influence of environmental contaminants on the immune system and therefore on the health status of marine mammals. Despite current efforts in the field of marine mammal immunology several aspects of the immune function in these marine mammal species remain unknown. However, the development of functional assays, such as the lymphocyte transformation assay enables the investigation of T and B cell immune response. Furthermore, natural killer cell activity, respiratory burst as well as the phagocytic and cytotoxic activity of leukocytes can be measured by immunological methods in different cetacean species. Humoral immune responses can be investigated by measuring different immunoglobulins in the serum of marine mammals, using radial immunodiffusion. Additionally, molecular-techniques, such as reverse transcription-polymerase chain reaction (RT-PCR) enable the detection and quantification of gene expression of pro- and anti-inflammatory cytokines in activated lymphoid cells during inflammation or immune responses. In combination with detailed clinical examinations, these immunologic methods represent important tools to assess the health status and susceptibility for infectious diseases in whales and dolphins. Several current studies demonstrate the association between environmental contamination and immunosuppression in different cetaceans and pinnipeds of different waters. However, species-specific differences of the immune system and metabolism of xenobiotics between whales and seals have to be taken into consideration in the interpretation of these results.