Page 509 - The Toxicology of Fishes

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The Immune System of Fish: A Target Organ of Toxicity

Erik Carlson and Judith T. Zelikoff

CONTENTS
Fish Immunology...................................................................................................................................489
Immune Cells ...............................................................................................................................490
Lymphoid Organs and Tissues.....................................................................................................490
Thymus ...............................................................................................................................490
Anterior Kidney..................................................................................................................491
Spleen..................................................................................................................................492
Mucosa................................................................................................................................492
Nonspecific Immunity..................................................................................................................493
Soluble Components...........................................................................................................493
Cellular Response...............................................................................................................495
Adaptive Immune Defense...........................................................................................................496
Humoral Immunity .............................................................................................................496
Cell-Mediated Immunity ....................................................................................................497
Immunomodulation by Chemicals.........................................................................................................497
Environmental Contaminants.......................................................................................................498
Metals..................................................................................................................................499
Pesticides.............................................................................................................................504
Halogenated Aromatic Hydrocarbons ................................................................................507
Polycyclic Aromatic Hydrocarbons....................................................................................510
Future Directions ...................................................................................................................................512
Conclusions............................................................................................................................................513
References..............................................................................................................................................513

Fish Immunology
Over the past few decades, our understanding of fish immunology has greatly progressed due to studies
utilizing molecular techniques, cell culture, and monoclonal antibodies. Most immunological research
involving fish species has been concerned with either their phylogenetic or economic importance; thus,
such groups as agnathans, elasmobranchs, and chondrosteans have been studied in attempts to elucidate
the evolution of the vertebrate immune system. Also, species such as salmonids (Oncorhynchus spp. and
Salmo spp.), carp (Cyprinus spp.), and catfish (Ictalurus spp.) have received interest mainly due to their
use in aquacultural settings. This section primarily focuses upon teleost fish and briefly reviews current
research in the area of fish immunology. The reader is directed toward reviews by Iwama and Nakanishi
(1996), Bernstein et al. (1998), and Pastoret et al. (1998) for additional information in this rapidly
expanding field. Following an introduction to the major lymphoid cells/tissues of teleosts, nonspecific
and specific components of the teleost immune system are presented in this chapter. Both cellular (i.e.,

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