Evidence of aberration of the natural cytotoxic cell activity in Fundulus heteroclitus (Pisces: Cyprinodontidae) from the Elizabeth River, Virginia.

There is a general agreement that exposure to high concentrations of polynuclear aromatic hydrocarbons (PAH) in sediments is associated with high frequencies of neoplasms in feral fish species. Since PAH modulate the activity of murine and amphibian natural cytotoxic (killer) cells, a leukocyte subpopulation that is believed to play an important role in immunosurveillance, we wished to determine if fish exposed to PAH could have an altered natural cytotoxic cell (NCC) activity. In the present study, mummichog (Fundulus heteroclitus L.) were collected from two sites in the Elizabeth River, VA that are heavily contaminated with PAH, and from a relatively unpolluted reference site in the York River, VA. The cytotoxic activity of anterior kidney and splenic leukocytes was tested against the tumor cell line K562. The leukocytes from Elizabeth River fish displayed a significant depression of the in vitro tumorilytic activity as compared with leukocytes from the York River fish. Analysis of leukocyte-tumor cell conjugates indicated that Elizabeth River fish leukocytes were unable to recognize and subsequently bind to the tumor target cells. This suggests an aberration in the early events of the cytotoxic mechanism. By keeping the fish in cleaner York River water for up to 28 weeks the suppressed NCC activity was reversed totally in one site, which is slightly contaminated, and partially in the other site, which is heavily polluted with creosote from an operating wood treatment plant. This indicates that the decreased NCC activity was related, at least in part, to exposure to the chemical pollutants in the Elizabeth River sediments.

Effect of tributyltin on chemiluminescent response of phagocytes from three species of estuarine fish.

The effect of in vitro exposure to tributyltin (TBT) on the chemiluminescent (CL) responses of kidney macrophages was examined in oyster toadfish (Opsanus tau), hogchoker (Trinectes maculatus) and Atlantic croaker (Micropogonias undulatus). Phagocytic activity was evaluated using a luminol-amplified chemiluminescent (CL) assay with zymosan as the stimulus. Following brief exposure to selected doses of TBT, the CL response of toadfish and hogchoker phagocytes was found to be significantly decreased at 400 micrograms/L TBT, while the croaker phagocytic activity was significantly decreased at 40 micrograms/L TBT. With 18 hr-exposure to TBT, the effect on the CL response was noticeable at lower doses (40 micrograms/L TBT for toadfish and 4 micrograms/L TBT for hogchoker).

Differential uptake of neutral red by macrophages from three species of estuarine fish.

Macrophage endocytosis is part of the immune response to foreign material and includes the processes of phagocytosis, ingestion of particulate material, and pinocytosis, the uptake of liquid droplets. This work reports the development of a quantitative method to measure in vitro uptake of neutral red by fish macrophages, based on the spectrophotometric measurement of ingested neutral red dye. We have used this method to monitor the rates of uptake in three species of fish: spot, Leiostomus xanthurus; hogchoker, Trinectes maculatus; and summer flounder, Paralichthys dentatus. For the species tested, there appeared to be an intrinsic pattern of uptake which was highest in flounder, lowest in hogchoker and intermediate in spot. The excellent reproducibility of this assay should make it useful for detecting toxicological effects in the environment.

Functional evaluation of macrophages in fish from a polluted estuary.

The chemotactic and phagocytic efficiencies of macrophages from spot, Leiostomus xanthurus and hogchoker, Trinectes maculatus are reported here. Fish were captured from the York and Ware Rivers, two relatively nonpolluted rivers, and from a reach of the Elizabeth River, known to be contaminated with high concentrations of polynuclear aromatic hydrocarbons (PAHs). Kidney cell types were separated by density gradient centrifugation and single cell suspensions of macrophages were used for in vitro studies. Chemotactic activity was measured in Boyden chambers using Escherichia coli as the chemotactic stimulus. The percentage of macrophages migrating was maximal at 90 min but was markedly reduced in Elizabeth River fish (spot, 33%; hogchoker, 56%) as compared to clean water controls (spot, 55%; hogchoker, 85%). Macrophage phagocytosis of bacteria was quantified by the microscopic enumeration of the proportion of phagocytes which contained intracellular bacteria. Phagocytic activity reached maximum values within 120 min and remained relatively constant for the remainder of the experiment. Phagocytic activity was reduced significantly in the fish obtained from the Elizabeth River. Values at 120 min were 74% and 19% for spot from the control and PAH-contaminated sites, respectively. Comparable values for hogchoker were 88% and 32%. The results suggest that defective macrophage function is related to exposure to PAH-contaminated sediments.

Severe oral lesions in chickens caused by ingestion of dietary fusariotoxin T-2.

Fusariotoxin T-2 is a mycotoxin produced by Fusarium tricinctum which was implicated in moldy corn toxicosis of farm animals. Graded concentrations of dietary fusariotoxin T-2 (0, 1, 2, 4, 8, and 16 mug/g, respectively) were given to groups of 40 chickens. Raised yellowish-white lesions on the mouth parts were produced by all concentrations, and the size of the lesions was dose-related. The growth rate was reduced significantly (P < 0.05) by concentrations of 4, 8, and 16 mug/g. The mouth fluid of the affected birds contained greatly increased numbers of bacteria, including Staphylococcus epidermidis and Escherichia coli, which proved avirulent when inoculated into scarified tissue of control birds. Microscopy examinations of the lesions revealed a fibrinous surface layer, intermediate layers containing invaginations filled with rods and cocci, and a heavy infiltration of the underlying tissues with granular leukocytes. These data suggest that the role of fusariotoxin T-2 in field cases of moldy corn toxicosis should be reinvestigated since oral lesions were not mentioned in the original descriptions of the disease. However, the lesions bear some features of those characteristic of the third or septic angina stage of alimentary toxic aleukia, a nutritional toxicosis of humans produced by eating grains infested with F. tricinctum.