Kidney Phagocytes Research Articles

Confinement stress in sea bass ( Dicentrarchus labrax) depresses peritoneal leukocyte cytotoxicity

Fish respond to stressful conditions via neuroendocrine responses (primary response) which result in increased levels of plasma cortisol which is considered immunosuppressive. Sea bass were confined at low (10 kg/m 3) and high (60 kg/m 3) density for 3–48 h. Plasma cortisol and glucose were evaluated and two principal cellular immune responses were assayed. A significant increase in plasma cortisol and glucose levels, as well as osmolarity, was found following stress. In addition, phagocytic activity, as shown by reactive oxygen species (ROS) production by challenged head kidney phagocytes and cytotoxic activity of eosinophilic granule cells from peritoneal cavity against K562 tumour cell lines appeared to be suppressed. Plasma levels of cortisol, glucose, osmolarity were correlated with cellular immunity, by the linear regression method. The suppression of cytotoxic activity was found to be significantly correlated with high plasma cortisol and glucose levels. These parameters could affect the eosinophilic granule cells of the peritoneal cavity.

Coho salmon Oncorhynchus kisutch strain differences in disease resistance and non-specific immunity, following immersion challenges with Vibrio anguillarum.

Two strains of freshwater-reared coho salmon Oncorhynchus kisutch were compared for differences in the activity of selected non-specific immune factors before and after lethal and non-lethal immersion challenges with the marine bacterial pathogen Vibrio anguillarum (Vang). Two disease challenge experiments were performed. The first experimental challenge resulted in no mortality; however, significant strain and challenge treatment effects were detected at Day 16 post-challenge. Strain differences in plasma lysozyme activity were found in pre-challenge samples. The second challenge experiment compared the same strains of coho salmon following immersion challenges in different doses of Vang. The fish were sampled at Days 0, 2, 7, and 18 post-challenge and mortality, plasma lysozyme, and anterior kidney phagocyte respiratory burst activity were compared. There were significant strain differences in mortality in the high dose group. The more disease-resistant strain was found to have higher levels of plasma lysozyme and anterior kidney phagocyte respiratory burst activity. These strain differences were detected at various times in the lethal (high dose) and non-lethal challenge groups. There was a clear relationship between the enhanced survival of the more disease-resistant strain and a more sustained, elevated non-specific immune response following the experimental disease challenges. The results of this study suggest that the basis for strain differences in innate disease resistance is related to the ability of the fish to respond quickly to the initial infection and to maintain the response until the infection is quelled.

Modulation of the in vitro activity of European sea bass (Dicentrarchus labrax L.) phagocytes by the myxosporean parasite Sphaerospora dicentrarchi (Myxosporea: Bivalvulida)

Several in vitro studies were performed to study the cellular reaction of European sea bass (Dicentrarchus labrax L.) against Sphaerospora dicentrarchi. Head kidney phagocytes were obtained from parasitised (P) and non-parasitised (NP) fish. The production of superoxide anion (O−2), tested by the NBT method, was higher in P than in NP fish. The addition of increasing amounts of sea bass serum (SBS) produced a gradual increment of the respiratory burst with SBS from parasitised animals (P-SBS), whereas this increment reached a plateau at lower concentration with SBS from non-parasitised ones (NP-SBS). O−2 production was higher when adding NP-SBS than with P-SBS or fetal bovine serum. Heat inactivation of NP-SBS and FBS reduced the respiratory burst significantly, whereas it did not change the effect of P-SBS. The number of NBT-positive cells after particulate stimulation was significantly higher using S. dicentrarchi spores than using SRBC, but lower than with phorbol myristate acetate. Phagocytes primed overnight with spore extracts produced higher amounts of O−2 than those LPS-primed or non-primed ones.A similar percentage of phagocytosis was detected using glutaradehyde fixed spores and SRBC. Most of the phagocytes engulfed three or more SRBC, whereas most of the phagocytes engulfed only one spore. Complement mediated opsonisation by NP-SBS may occur, as the phagocytic index was reduced when the serum was heat inactivated.

Comparative effects of UVA and UVB irradiation on the immune system of fish

Aquatic organisms can be harmed by the current levels of solar ultraviolet radiation. We have recently shown that exposure of fish to UVB irradiation alters the functioning of the fish immune system, but the effects of UVA radiation are unknown. The present study continues this work by characterizing UVA irradiation-induced immunological changes in fish. Roach, a cyprinid fish, were exposed to a single dose of either UVA (3.6 J/cm 2) or UVB (0.5 J/cm 2) irradiation. Both irradiations suppressed transiently mitogen-stimulated proliferation of blood lymphocytes. UVA, but not UVB, decreased hematocrit, plasma protein, and plasma immunoglobulin levels and increased the proportions of blood cells classified as unidentified leukocytes, possibly consisting of UVA-damaged lymphocytes. UVB, but not UVA, altered the functioning of head kidney and blood phagocytes, induced granulocytosis and lymphocytopenia in the blood and increased plasma cortisol concentration. These results imply that both UVA and UVB are potent modulators of the immune defence of fish.

Pollutant-induced over-activation of phagocytes is concomitantly associated with peroxidative damage in fish tissues

Pollutant-induced abnormal functioning of phagocytes and associated consequences were studied in freshwater catfish Heteropneustes fossilis (Bloch). Fish were exposed to effluent collected from bleached kraft type of paper mill at the concentration levels of 0.5, 1 and 2% for 15, 30, 60 and 90 days. Respiratory burst activity of peritoneal and head kidney phagocytes of exposed fish was measured by nitroblue tetrazolium reduction assay. Lipid peroxidation (LPO) was estimated in liver, gill and kidney of fish by measuring thiobarbituric acid reaction substances. It was observed that the phagocyte-activating xenobiotics of effluent induced an increase in the respiratory burst activity in phagocytes. The induction of respiratory burst activity was concomitantly associated with an increase in the peroxidative damage of tissues. The tissues most affected were kidney and gills. The change in LPO values in the gills of exposed fish was concentration- and time-dependent, showing significant increases ( P<0.05 to <0.001) in all the exposed groups as compared with control fish. An almost similar pattern of LPO was observed in head kidney tissue ( P<0.05 to <0.001). As regards liver, increase in LPO was not widespread, except at 0.5% for 90 days ( P<0.05). In fact, reduced rates of LPO were observed in the livers of some groups. The results of respiratory burst corroborate with the phagocytic activation as well as with the extent of lipid peroxidation in the tissues, showing high population of circulatory phagocytes. Our results demonstrate that fish of polluted water are subjected to oxidative stress of multifarious dimensions.

Lindane differently modulates intracellular calcium levels in two populations of rainbow trout ( Oncorhynchus mykiss) immune cells: head kidney phagocytes and peripheral blood leucocytes

We studied the in vitro effects of high concentrations of the insecticide lindane (from 2.5 to 100 μM) on intracellular calcium levels ([Ca 2+] i) in rainbow trout head kidney phagocytes and peripheral blood leucocytes (PBLs). [Ca 2+] i was measured during 6 min by spectrofluorimetry using Indo-1/AM as fluorescent probe. Lindane, from 5 to 100 μM, increased [Ca 2+] i in PBLs and from 25 μM in phagocytes. In Ca 2+-free medium, only 50 and 100 μM lindane increased significantly [Ca 2+] i in PBLs and only 100 μM lindane in phagocytes. However, lindane at 5 and 10 μM, induced a decrease in [Ca 2+] i in phagocytes suspended in Ca 2+-free medium. Lindane needed extracellular calcium to rise [Ca 2+] i in phagocytes but not in PBLs. Lindane effects on endoplasmic reticulum (ER) calcium store was examined. In spite of mobilisation by lindane of ER calcium store in phagocytes, it had an opposite effect in PBLs. The composition of the two cell population can explain the differences in calcium modulation observed. [Ca 2+] i is an extremely important signal transduction element in physiology and modulation of [Ca 2+] i by lindane can be responsible for modulations of immune cell functions. Moreover, sustained rises in [Ca 2+] i as observed in our study may be associated with cell death and explained partially the cytotoxicity of this organochlorine insecticide on fish immune cells.

Lindane increases in vitro respiratory burst activity and intracellular calcium levels in rainbow trout ( Oncorhynchus mykiss) head kidney phagocytes

Phagocytic cells are the main actors of the fish immune system. They secrete reactive oxygen species (ROS) involved in their bactericidal activity. The effects of lindane on ROS production in rainbow trout phagocytes are contradictory. Here, we study the effects of high concentrations of lindane on ROS production (by chemiluminescence) and on intracellular calcium levels ([Ca 2+] i) (by spectrofluorimetry) in trout phagocytes. In these cells, lindane from 2.5 to 10 μM, increases ROS production and has no effect on [Ca 2+] i. From 25 to 200 μM, lindane leads to a rise in ROS production (maximal value measured: 41 152±6253 RLU for 100 μM lindane) associated with an increase in [Ca 2+] i (+3149±96 nM for 100 μM lindane) and with cytotoxicity which appears 2 min after addition of 100 μM lindane (25.4±3.75%; P<0.05). In the absence of extracellular calcium, ROS production of lindane-treated cells remains significantly higher than in controls (maximal value measured: 1899±254 RLU for 25 μM lindane), a significant decrease in [Ca 2+] i is observed in cells treated with 5 or 10 μM lindane (−54±35 nM for 10 μM lindane), and an increase in [Ca 2+] i in cells treated with 100 μM lindane (330±33 nM). The rise in [Ca 2+] i induced by lindane is inhibited when cells are preincubated with thapsigargin (Thaps). We conclude that lindane induces an increase in [Ca 2+] i by mobilising the endoplasmic reticulum calcium store. High concentrations of lindane (>50 μM) alter Ca 2+ homeostasis in the absence of extracellular Ca 2+, confirming that lindane can affect other intracellular stores of Ca 2+. At low concentrations (<25 μM), lindane stimulates ROS production by Ca 2+-independant mechanisms without inducing cytotoxicity. From 25 μM, lindane increases [Ca 2+] i and maximal cytotoxicity appears from 100 μM lindane. Lindane toxicity in fish phagocytes may be associated with high [Ca 2+] i and high ROS production. Thus, ROS are beneficial in protection of the organism but when ROS are produced in excess, they can be toxic for cells and tissues.

Nutritional impacts on the chemiluminescent response of Atlantic salmon (Salmo salar L.) head kidney phagocytes, in vitro

Measurement of an induced chemiluminescent response of Atlantic salmon (Salmo salar L.) head kidney phagocytes preincubated in plasma preparations varying in vitamin E, vitamin C, astaxanthin, copper (Cu), iron (Fe), manganese (Mn), zinc (Zn), cholesterol, triglycerides (TAG), glucose, and total protein concentrations were performed in order to determine nutritional in vitro effects on the amount of reactive oxygen species (ROS) produced during respiratory burst activity of these cells. Phorbol myristate acetate was used to stimulate the respiratory burst, and luminol was used as substrate. These plasma preparations were obtained from Atlantic salmon fed diets containing high or low levels of selected dietary pro-and antioxidants using a reduced factorial design. Plasma vitamin C and glucose significantly inhibited the generation of chemiluminescence measured as response curve area. There was also a tendency to an inhibitory effect of plasma Zn. A negative correlation between plasma Mn and chemiluminescent response was observed only at high concentrations of plasma vitamin C. Plasma concentrations of vitamin E, astaxanthin, Cu, Fe, cholesterol, TAG, and total protein showed no effects on the generation of ROS.

MAMMALIAN IMMUNOASSAYS FOR PREDICTING THE TOXICITY OF MALATHION IN A LABORATORY FISH MODEL

Abstract This study describes the use of a panel of immune assays, originally developed by the National Toxicology Program for assessing xenobiotic-induced immunotoxicity in mice, to quantify the effects of sublethal malathion exposure on the immune responses of fish. For this study, Japanese medaka (Oryzias latipes) were exposed subchronically to the organophosphate pesticide malathion in a series of two experiments. In the first set of studies, fish were exposed for 7 or 14 d to untreated well water (i.e., controls) or to waterborne malathion at 0.2 or 0.8 mg/L. Following exposure, fish from each group were sacrificed and their kidneys (primary organ of leukopoiesis in fish and equivalent to mammalian bone marrow) were used to provide cells for assessing any malathion-induced effects upon nonspecific and acquired immune defense mechanisms. Effects upon humoral-mediated immunity were determined by enumerating antibody plaque-forming cell (PFC) numbers from a subset of fish exposed to malathion for 14 d and then injected intraperitoneally (ip) with sheep erythrocytes (sRBC). Results of these studies demonstrated that while malathion exposure had no significant effect upon hematocrit/leukocrit values or upon mitogen-stimulated T-cell lymphoproliferation, PFC numbers in the kidney of exposed fish were significantly reduced (compared to control fish) in a dose-dependent manner. In addition, total recoverable kidney cell numbers and viability, as well as superoxide anion production by kidney phagocytes, were reduced slightly (compared to control values) in fish exposed for 14 d to the highest malathion concentration tested. In the second set of experiments, medaka exposed for up to 21 d to either 0.1 or 0.3 mg malathion/L were challenged ip with an LD50 dose of the bacterial fish pathogen Yersinia ruckeri. Results from these infectivity studies demonstrated that exposure to either malathion concentration for 14 or 21 d reduced host resistance against Yersinia infection. Taken together, these findings demonstrate the applicability of mammalian immune assays for predicting malathion-induced immunosuppression in a teleost fish, as well as the potential utility of a small laboratory fish to serve as an alternate model for mammals in immunotoxicological studies.

Mammalian Immunoassays for Predicting the Toxicity of Malathion in a Laboratory Fish Model

This study describes the use of a panel of immune assays, originally developed by the National Toxicology Program for assessing xenobiotic-induced immunotoxicity in mice, to quantify the effects of sublethal malathion exposure on the immune responses of fish. For this study, Japanese medaka (Oryzias latipes) were exposed subchronically to the organophosphate pesticide malathion in a series of two experiments. In the first set of studies, fish were exposed for 7 or 14 d to untreated well water (i.e., controls) or to waterborne malathion at 0.2 or 0.8 mg/L. Following exposure, fish from each group were sacrificed and their kidneys (primary organ of leukopoiesis in fish and equivalent to mammalian bone marrow) were used to provide cells for assessing any malathion-induced effects upon nonspecific and acquired immune defense mechanisms. Effects upon humoral-mediated immunity were determined by enumerating antibody plaque-forming cell (PFC) numbers from a subset of fish exposed to malathion for 14 d and then injected intraperitoneally (ip) with sheep erythrocytes (sRBC). Results of these studies demonstrated that while malathion exposure had no significant effect upon hematocrit/leukocrit values or upon mitogen-stimulated T-cell lymphoproliferation, PFC numbers in the kidney of exposed fish were significantly reduced (compared to control fish) in a dose-dependent manner. In addition, total recoverable kidney cell numbers and viability, as well as superoxide anion production by kidney phagocytes, were reduced slightly (compared to control values) in fish exposed for 14 d to the highest malathion concentration tested. In the second set of experiments, medaka exposed for up to 21 d to either 0.1 or 0.3 mg malathion/L were challenged ip with an LD50 dose of the bacterial fish pathogen Yersinia ruckeri. Results from these infectivity studies demonstrated that exposure to either malathion concentration for 14 or 21 d reduced host resistance against Yersinia infection. Taken together, these findings demonstrate the applicability of mammalian immune assays for predicting malathion-induced immunosuppression in a teleost fish, as well as the potential utility of a small laboratory fish to serve as an alternate model for mammals in immunotoxicological studies.

Alpha-melanocyte stimulating hormone (α-MSH) and melanin-concentrating hormone (MCH) stimulate phagocytosis by head kidney leucocytes of rainbow trout (Oncorhynchus mykiss) in vitro

Alpha-melanocyte stimulating hormone (α-MSH) and melanin-concentrating hormone (MCH) are two peptides with antagonistic roles in the regulation of skin pigmentation in teleost fish. Both have also been implicated in the modulation of the stress response via the hypothalamo-pituitary-adrenal (HPA) axis in fish and other vertebrates. Alpha-MSH is also known to be a potent immunomodulatory peptide in mammals, while both hormones have been shown to influence the immune responses of troutin vitro. Head kidney phagocytes (macrophages and neutrophils) were exposed to α-MSH at concentrations of 0·05 to 10nMin vitro for 60min and the phagocytic activity of glass-adherent cells was assessed microscopically. At 1, 5 and 10nMα-MSH significantly increased the percentage of phagocytes that ingested heat-killed yeast cells. Percentage phagocytosis was also significantly increased when cells were exposed to 0·1, 1 and 10nM des-acetyl-α-MSH. Whenα-MSH and MCH were added to cells together, at concentrations of 1nM and 50nM respectively, the stimulatory effects of both hormones were diminished. The results suggest that these peptides may play an immunomodulatory role in the fish immune system.

Melanin-concentrating hormone (MCH) stimulates the activity of rainbow trout (Oncorhynchus mykiss) head kidney phagocytes in vitro

Melanin-concentrating hormone (MCH) is a widespread vertebrate neuropeptide first discovered in teleost fish by virtue of its role in the control of skin pigmentation. In rainbow trout, its release from the pituitary gland causes aggregation of melanin granules in dermal melanophores, thus lightening the colour of the skin (Rance & Baker, 1979). Another hormone, alpha-melanocyte stimulating hormone (a-MSH) has the opposite e#ect and results in skin darkening, a response common to teleosts, amphibians and reptiles (Baker, 1993). In vertebrates other than fish, MCH does not circulate as a hormone, but probably acts centrally as a neuromodulator (Baker, 1994). The peptide is known to be involved in the stress response and modulates the release of corticotrophin-releasing factor (CRF) from the hypothalamus of both fish and mammals (Baker, 1994). Evidence also suggests that MCH inhibits the release of a-MSH and adrenocorticotrophic hormone (ACTH) from the trout pituitary (Baker et al., 1985; Green & Baker, 1991). In mammals, the peptide stimulates the production and release of arginine-vasopressin (AVP) and oxytocin from the hypothalamus (Parkes & Vale, 1993). Other functions of MCH have yet to be elucidated, but it has been shown to antagonise the stimulatory e#ects of a-MSH on both the response to auditory stimuli (Miller et al., 1993) and grooming behaviour (Eberle, 1988) in rats. Whilst a-MSH is known to exert a variety of e#ects on the mammalian immune system (Lipton & Catania, 1997), the possibility that MCH may be involved in vertebrate immune responses has received little attention so far. It has been demonstrated that MCH antagonises the stimulatory e#ects of a-MSH on fish head kidney leucocytes in vitro (Harris & Bird, 1997). Here, it is shown that MCH can also directly influence the activity of rainbow trout (Oncorhynchus mykiss) phagocytes in vitro.

Biomarkers of immunotoxicity in fish and other non-mammalian sentinel species: predictive value for mammals?

Through the efforts of different laboratories, a battery of immunological assays is available to predict the immunotoxicity of xenobiotics. These assays, originally developed in rodents, have been adapted for use in a variety of animal species and are now used routinely in these models to assess the immunotoxicity of different chemical classes. For example, our laboratory has employed assays that measure antibody-forming cell response to T-dependent antigens, T- and B-cell lymphoproliferation, macrophage function, and host resistance against infectious bacteria to assess metal-induced immunotoxicity in laboratory-reared Japanese medaka ( Oryzias latipes); immunologically-related assays measuring antioxidant activity have also been used in this capacity. Results of the aforementioned investigations have shown the usefulness of these endpoints to reliably demonstrate chemical-mediated immunotoxicity in teleost systems. Many of these same endpoints have also proved successful for predicting the immunotoxic effects of contaminated aquatic environments in feral fish populations. For example, smallmouth bass collected from a chlorinated hydrocarbon-contaminated site demonstrated significant changes in blood cell profiles and kidney phagocyte function compared to fish collected from a ‘clean water’ reference site. Some of these same immune parameters have also been used successfully to predict the immunotoxicity of polluted aquatic environments in feral populations of fish-eating birds and harbor seals. While interspecies extrapolation is difficult and should be approached with caution due to variables such as metabolism and pharmacokinetics, results from these studies demonstrate the usefulness of these immune assays to predict the immunomodulating effects of xenobiotics in fish and other wildlife species, as well as the applicability of fish to serve as additional/alternate animal models for mammalian species in immunotoxicological studies.

Phagocytic and Metabolic Activities of Macrophages from Mummichog Naturally Exposed to Pulp Mill Effluents in the Miramichi River

Chemicals present in bleached kraft pulp mill effluents (BKMES) can modulate the immune response of fish. This work was conducted to determine if mummichogs living downstream from a bleached kraft pulp mill (BKM) had an impaired immune response. Head kidney phagocytes from males and females were tested for their phagocytic and metabolic activities. Mummichogs were captured 4 km (S2) and 39 km (S1) downstream from a BKM in the Miramichi estuary (New Brunswick, Canada) and at two sites located upstream (S3) and 20 km downstream (S4) in a reference estuary, the Bouctouche. Both male and female mummichogs captured at S2 in the Miramichi estuary had a lower phagocytic activity, whereas only females from the same site had a decreased oxidative burst response, indicating a difference between sexes in the susceptibility to pollutants present in the Miramichi. Therefore, the results indicate that mummichogs exposed to BKMES have an impaired immune response and that females are more sensitive than males to the chemicals present in BKMES.

Effects of dietary PCBs and nonyl-phenol on immune function and CYP1A activity in channel catfish, Ictalurus punctatus

Polychlorinated biphenyls (PCBs) induce CYP1A, modulate immune responses, and may have endocrine disruption properties. Many coastal ecosystems and their tributaries contaminated with PCBs also receive sewage out-fall effluents containing detergents such as nonyl-phenol (NP). Because NP has estrogenic properties and modulates P4501A activity, and because estrogen modulates immune function in a variety of vertebrates, studies to investigate interactions of PCBs and NP are needed. Channel catfish ( Ictalurus punctatus) (25–30 g) were fed seven different diets containing 10 ppm Aroclor 1254 (PCB), 10 ppm NP, Wppm PCB + 10 ppm NP, 100 ppm PCB + 10 ppm NP, 10 ppm PCB + 100 ppm NP, 100 ppm of each, or carrier. After 7 and 21 days of treatment peripheral blood hematocrits, total serum protein and immunoglobulin, antigen-specific antibody, anterior kidney phagocyte oxidative burst, and gut/liver cytochrome P4501A protein/EROD, were evaluated. Phagocyte function was enhanced by low NP on day 7 and low PCB + high NP on day 21. Gut and liver P4501A protein/EROD were greatly induced by combinations of high PCB + high and low NP. Treatments did not effect hematocrits, serum protein or total immunoglobulin on either day or antibody titers on day 21 against formalin-killed Edwardsiella ictualuri (day 14 post sensitization).

Modulation of superoxide production in goldfish (Carassius auratus) exposed to and recovering from sublethal copper levels

The effects of copper and recovery from sublethal (100μg/l) copper exposure were studied in three groups of goldfish (Carassius auratus) (1) control (2) copper (4–25d) and (3) recovery (4d exposure followed by 3–21d recovery). The mean concentration of copper measured in the liver of the continuously exposed group was significantly higher than in the control and recovery groups by 11 and 18 days of exposure, respectively. In the posterior kidney, copper accumulation in the copper group was not significantly greater than the control and recovery groups until 18 days of exposure. The liver contained 4–5-fold higher concentrations of copper than the posterior kidney in all three treatment groups. Levels of copper in the posterior kidney correlated with those of the anterior kidney. There were no measurable differences in liver, kidney, or serum copper levels within or between the control and recovery groups at any time point. The production of superoxide (O2−) was compared between groups by measuring the reduction of NBT in anterior kidney phagocytes. In the copper group, production of O2−increased compared to controls in response to exposure periods lasting up to 11 days. O2−production in the recovery group also increased in response to 4 days of copper exposure. However, after 3 and 7 days of recovery, O2−production decreased below then increased above the control levels, respectively. By 18 days of copper exposure or 14 days of recovery, O2−production was no longer significantly different from control values. To determine if the decreased O2−production measured on recovery day 3 was mediated by a humoral factor, phagocytes from untreated fish were incubated with serum from control or 3d recovery fish. Compared to the control serum,in vitroexposure to serum from copper-recovered animals resulted in a 29–34% decrease in O2−production. This was consistent with the 25% decrease measured in phagocytes from copper-recovered animals. It is concluded that the decrease in O2−production demonstrated in goldfish recovering 3 days from acute (4d) sublethal copper exposure is not due to a direct effect of copper but to a factor(s) present in the serum of the recovering animals.

Modulation of the respiratory burst activity of Mediterranean sea bass (Dicentrarchus labraxL.) phagocytes by growth hormone and parasitic status

The immunoregulatory role of GH in sea bass (Dicentrarchus labrax), in relation to the intensity of infection by the myxosporean parasiteSphaerospora dicentrarchi, was investigated. Thein vitrodetection of superoxide anion (O2−) in head kidney phagocytes was optimised using the nitroblue tetrazolium (NBT) assay. O2−production was proportional to the quantity of total protein per well, and 15 and 30 min of PMA triggering gave the highest stimulation index. Cells adhered overnight produced more O2−than cells adhered for 3h. Trifluoperazine abolished the reduction of NBT almost completely, whereas superoxide dismutase only caused 37·4% inhibition. Cells from fish parasitised byS. dicentrarchi, produced higher levels of O2−compared with non-parasitised fish. Overnight priming with 5nMrecombinant rainbow trout growth hormone (rtGH) produced a significant increase in the respiratory burst of phagocytes from non-parasitised fish. Phagocytes from fish with medium intensity of infection attained the maximum response at 50nMand 150nMrtGH. LPS (20μg ml−1) priming did not induce an increase in O2−production, but it significantly increased cell adherence in non-parasitised fish.

Effects of sodium alginate on the non-specific defence system of the common carp (Cyprinus carpioL.)

Carp which receive intraperitoneal injections of sodium alginate show a high survival rate after being challenged withEdwardsiella tarda. In order to elucidate the immunoenhancement by sodium alginate, its effects on the non-specific defence system of carp were investigated. Sodium alginate had little influence either on the activity of the alternative complement pathway or on the phagocytic and respiratory burst activities of head kidney phagocytes (HKP), yet it greatly enhanced the migration of HKP to the peritoneal cavity (the site of injection) and concurrently elevated their phagocytic activity. The number of phagocytes mobilised by sodium alginate was 2 to 50 times greater than that by the well-known peritoneal exudate cell-eliciting agents when injected at the same dose. Accordingly, it is highly probable that the early elimination of challenge bacteria by such mobilised and activated phagocytes was responsible for the high survival rate of the alginate-injected fish. In chemotaxis assays, it was revealed that sodium alginate stimulated some leucocyte subpopulation(s) within the peritoneal cavity to produce and/or secrete chemotactic factor(s), whilst concurrently enhancing the sensitivity of HKP to the factor(s).

A cell capsule with possible involvement in resistance to opsonophagocytosis in Enterococcus seriolicida isolated from yellowtail Seriola quinqueradiata

DAO Diseases of Aquatic Organisms Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials DAO 29:233-235 (1997) - doi:10.3354/dao029233 A cell capsule with possible involvement in resistance to opsonophagocytosis in Enterococcus seriolicida isolated from yellowtail Seriola quinqueradiata Yoshida T, Endo M, Sakai M, Inglis V A cell capsule was revealed by transmission electron microscopy on the surface of non-agglutinating (KG-), but not on agglutinating (KG+), cells of the bacterial fish pathogen Enterococcus seriolicida. The capsule of KG- cells may be involved in resistance to opsonophagocytosis by head kidney phagocytes of yellowtail Seriola quinqueradiata. Capsule · Fish pathogen · Anti-opsonophagocytosis · Enterococcus seriolicida · Seriola quinqueradiata Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in DAO Vol. 29, No. 3. Publication date: June 19, 1997 Print ISSN:0177-5103; Online ISSN:1616-1580 Copyright © 1997 Inter-Research.

Effect of in vivo cadmium exposure on the respiratory burst of Marine Fish ( Limanda limanda L.) phagocytes

Following the in vivo exposure of dab ( Limanda limanda L.) to cadmium chloride, kidney phagocytes were collected and their respiratory burst measured in vitro using chemiluminescence. Fish were exposed to mean measured concentrations of 1.3, 2.7 and 5.5 mg Cd litre −1 (as total cadmium ion) for a total of nine weeks, followed by a three week depuration period in clean sea water. Compared with control fish, the respiratory burst of kidney phagocytes from dab sampled after six weeks was significantly reduced in the 2.7 and 5.5 mg Cd litre −1 treatments (Steel's test, p < 0.05). Significant reductions were observed in the respiratory burst of phagocytes from all cadmium exposed fish compared with control fish after nine weeks (Steel's test, p < 0.05). After a further three week depuration period in clean sea water, the respiratory burst of phagocytes from fish previously exposed to 1.3 and 2.7 mg Cd litre −1 were still significantly less than in the control group (Steel's test, p < 0.05). Muscle tissue cadmium concentrations were also analysed, although there was no clear relationship between the muscle total cadmium levels and kidney phagocyte chemiluminescence. The results are discussed with respect to the possible mechanism(s) of cadmium immunotoxicity in dab and recommendations made for future work.