ABSTRACT

Fish exposed to toxic pollutants both in the wild and in the laboratory show significant changes in the immune activity of kidney macrophages. Decreases in the chemotactic and phagocytic responses and increases in neutral red uptake and melanin accumulation were observed in several species of fish captured in the Elizabeth River, Virginia, which is highly contaminated with polynuclear aromatic hydrocarbons. A high proportion of the fish collected from the Elizabeth River exhibits cataracts, fin rot, and integumental lesions. Fish exposed to Elizabeth River sediments in the laboratory develop signs ranging from fin loss, severe skin lesions, cataracts, gill hyperplasia, and liver and pancreatic necrosis to death. Macrophages are an important part of the cellular immune system of fish and function as the first line of defense by ingesting foreign material including disease-causing agents. During phagocytosis, fish macrophages show a burst of oxygen consumption associated with the production of microbicidal reactive oxygen species that emit detectable light upon relaxation.