Phagocytic Ability Of Neutrophils Research Articles

Killer Function of Circulating Neutrophils in Relation to Cytokines in Uterine Myoma and Endometrial Cancer.

The study presents the killer functions of circulating neutrophils: myeloperoxidase activity, the ability to generate ROS, phagocytic activity, receptor status, NETosis, as well as the level of cytokines IL-2, IL-4, IL-6, IL-17A, and IL-18, granulocyte CSF, monocyte chemotactic protein 1, and neutrophil elastase in the serum of patients with uterine myoma and endometrial cancer (FIGO stages I-III). The phagocytic ability of neutrophils in uterine myoma was influenced by serum levels of granulocyte CSF and IL-2 in 54% of the total variance. The degranulation ability of neutrophils in endometrial cancer was determined by circulating IL-18 in 50% of the total variance. In uterine myoma, 66% of the total variance in neutrophil myeloperoxidase activity was explained by a model dependent on blood levels of IL-17A, IL-6, and IL-4. The risk of endometrial cancer increases when elevated levels of monocyte chemotactic protein 1 in circulating neutrophils are associated with reduced ability to capture particles via extracellular traps (96% probability).

EQUOL, A SOYBEAN METABOLITE WITH ESTROGEN-LIKE FUNCTIONS, DECREASES LIPOPOLYSACCHARIDE-INDUCED HUMAN NEUTROPHIL EXTRACELLULAR TRAPS IN VITRO.

Objective: Neutrophil extracellular traps (NETs) defend against acute infections. However, their overexpression causes organ failure during sepsis. Control of NET formation may improve the outcomes of patients with sepsis. Equol, a soybean isoflavone, is a female hormone analog, which prevents inflammation. We evaluated the effects of equol on NET formation in human neutrophils during inflammatory stimulation in vitro . Methods: Healthy volunteers provided blood samples. An enzyme-linked immunosorbent assay assessed serum equol concentrations. Neutrophil extracellular trap formation in neutrophils was induced by lipopolysaccharide treatment. Enzyme-linked immunosorbent assay quantified DNA-binding elastase, and immunostaining assessed NET formation. Reverse-transcription quantitative polymerase chain reaction and Western blotting detected G-protein-coupled receptor 30 (GPR30) or peptidyl arginine deiminase 4 (PAD4) expression. Flow cytometry assessed neutrophil phagocytic ability with inactivated Escherichia coli . Results: In neutrophils derived from males with low-serum equol levels (low-serum equol group), equol significantly decreased DNA-binding elastase levels and NET formation. Equol did not decrease NETs in neutrophils from males with high-serum equol levels. GPR30 expression of neutrophils was higher in the low-serum than in the high-serum equol group. PAD4 mRNA levels and nuclear PAD4 protein expression also decreased more than the vehicle control in the low-serum equol group. Equol did not alter the phagocytic ability of neutrophils. In neutrophils from young females, equol had no inhibitory effect on NET formation. Conclusions: Equol decreases lipopolysaccharide-induced NET formation in neutrophils from males via inhibition of PAD4 expression. Our findings provide a rationale for investigating a new therapeutic approach using equol to control neutrophil activity during sepsis.

Evaluation of pre- and post-dilution continuous veno-venous hemofiltration on leukocyte and platelet function in patients with sepsis.

We investigated the differences in biocompatibility pre- and post-dilution during continuous veno-venous hemofiltration in patients with sepsis, focusing on leukocyte and platelet function. Subjects were 12 patients with septic shock who underwent veno-venous hemofiltration for acute kidney injury between March 2016 and September 2017. The first six patients received pre-dilution veno-venous hemofiltration, and the next six patients received post-dilution veno-venous hemofiltration. The blood flow rate and filtration flow rate for veno-venous hemofiltration using a polysulfone hemofilter were set to 150 and 35 mL/min, respectively. Leukocyte and platelet counts were determined at 0 and 24 h after veno-venous hemofiltration commencement. Serum interleukin-6 and interleukin-10 levels, the induction rates of regulatory T cells, the expression rate of monocyte HLA-DR, neutrophil phagocytic and sterilizing ability, and platelet P-selectin expression rate were determined at 0, 6, and 24 h after veno-venous hemofiltration commencement. There were no significant differences in patient characteristics between the two groups. Serum interleukin-6 decreased over time during pre- and post-dilution veno-venous hemofiltration. Serum interleukin-10 levels decreased during pre-dilution veno-venous hemofiltration, but remained unchanged during post-dilution veno-venous hemofiltration. The Treg and platelet P-selectin expression rates significantly increased at 24 h compared to 0 h during post-dilution veno-venous hemofiltration. Neutrophil phagocytic ability at 24 h was significantly decreased compared to that at 0 h during post-dilution veno-venous hemofiltration. No significant changes in leukocyte and platelet function were observed during pre-dilution veno-venous hemofiltration. Pre-dilution veno-venous hemofiltration demonstrates superior biocompatibility in terms of decreased leukocyte function and platelet activation in septic shock patients with acute kidney injury.

Intracellular reactive oxygen species production and phagocytosis of Staphylococcus aureus by milk neutrophils as tool to diagnose mastitis and identify susceptible dairy cows

ABSTRACT: The immune response capacity of the mammary gland plays a major role to determine if mastitis will or not be established. Thus, we hypothesize that a better understanding of polymorphonuclear neutrophil leukocyte (PMN) function will elucidate mechanisms that will improve our knowledge of how we could avoid an inflammatory process by increasing the immune capacity of the cow, and even further, to search for a tool to diagnose mastitis or a possible way to select and identify non-susceptible animals. The present study utilized 112 quarters from 28 Holstein dairy cows that were divided into quarters milk samples with somatic cell count (SCC) <2×105 cells mL-1 (n=72) and SCC >2×105 cells mL-1 (n=40). The percentages of milk PMNs and the levels of intracellular reactive oxygen species (ROS) and the phagocytosis of Staphylococcus aureus by milk neutrophils were evaluated by flow cytometry. Our results showed a higher percentage of neutrophils in quarter milk samples with high SCC (P=0.0003), and this group also had a significantly higher percentage of neutrophils that produced ROS (P=0.008). On the other hand, the phagocytosis intensity of S. aureus by milk neutrophils was higher in quarters with low SCC (P=0.003), suggesting a better mammary gland immunity against invading pathogens. Analyzing the results of the predictive values of the measured PMN functions, they cannot be used isolated as a good diagnosis test since none of them had a satisfactory sensitivity and specificity values, which was also confirmed by the Youden index values being far from one. In conclusion, the assessment of milk bovine neutrophil functions could improve our understanding of the cellular basis of mastitis. Although, the intracellular ROS production and S. aureus phagocytosis by milk neutrophil did not have high predictive values to detect intramammary infections, our results strengthen the idea that that poor bovine mammary gland neutrophil phagocytic ability may be associated with high SCC, and might be considered to identify susceptible dairy cows to mastitis.

Short communication: Effects of an immunomodulatory feed additive on phagocytic capacity of neutrophils and relative gene expression in circulating white blood cells of transition Holstein cows

High-producing dairy cows typically experience immunosuppression with dysregulated neutrophil function (e.g., compromised phagocytosis) during the transition period (3 wk before to 3 wk after parturition), which is causally associated with increased risk of infections. Enhanced neutrophil immune competence has significant bearing with the wellbeing of transition dairy cattle. In the current study, we investigated the effect of OmniGen-AF (OG; Phibro Animal Health, Quincy, IL) and its dose in modulation of neutrophil function of transition cows. Forty-eight multiparous cows were stratified by parity, somatic cell count, and expected calving date and randomly assigned to 3 treatments: OG fed at 0 g/head per day (CON), 60 g/head per day (OG60; recommended dose), and 90 g/head per day (OG90; 1.5× recommended dose). The OG was added from dry off (61.8 ± 1.69 d before parturition) to 28 d in milk (DIM), and removed from all treatment groups at 29 to 35 DIM (the last week of the experimental period). Neutrophil phagocytic ability against Staphylococcus aureus and Escherichia coli was improved and tended to be improved, respectively, by OG from d 28 before parturition to 28 DIM. Cows in OG60 had higher neutrophil phagocytic ability against S. aureus and E. coli compared with CON cows from d 28 before parturition to 28 DIM. Neutrophil phagocytosis of S. aureus and E. coli was higher and tended to be higher for OG60 compared with CON on 35 DIM. The relative gene expression of CXCL8 and SELL were upregulated and tended to be upregulated by OG from 60 d before parturition to 28 DIM; this was due to cows in OG60 having greater SELL and CXCL8 gene expression than CON. Expression of SELL in circulating white blood cells of OG60-treated cows was greater than OG90 and the relative expression of CXCL8 gene tended to be greater for OG60 compared with CON on 35 DIM. In conclusion, feeding OG at the recommended dose of 60 g/head per day from dry off was effective in maintaining peripheral blood neutrophil function in transition dairy cows, and it is not necessary to feed OG beyond the recommended dose.

TLR expression, phagocytosis and oxidative burst in healthy and septic newborns in response to Gram-negative and Gram-positive rods

The objective was to investigate whether phagocytes from healthy and septic newborns have a developmental deficiency in their capacity to recognize, phagocytize and generate hydrogen peroxide (H2O2) in response to Escherichia coli and Staphylococcus aureus. TLR expression and phagocytic ability of neutrophils and monocytes from 44 healthy preterm and term neonates, from 13 newborns with late-onset sepsis and from 24 healthy adults were determined using flow cytometry, and H2O2 production was measured by dihydrorhodamine test. TLR-2 and TLR-4 expressions were similar among the groups. The phagocytic ability of monocytes and neutrophils exposed to E. coli and S. aureus in healthy and septic neonates was significantly reduced compared to that of adults. Monocytes from septic newborns exposed to E. coli had higher H2O2 production than those of the other groups. The oxidative burst of monocytes exposed to S. aureus was reduced in preterm newborns compared with term ones and those with sepsis, and no differences were found in the oxidative burst of neutrophils. Even with the ability to recognize bacteria, a decreased clearance of pathogens can cause an imbalance in the immune response, which could lead to a predisposition to sepsis. Once established, the increased production of cytokines and ROS in an attempt to control the infection as well as the lack of full phagocytic activity leads to persistence of the pathogen and a state of constant inflammation.

Lipoxin A4 augments host defense in sepsis and reduces Pseudomonas aeruginosa virulence through quorum sensing inhibition.

Bacterial infections can quickly turn into sepsis, with its attendant clinical sequelae of inflammation, tissue injury, and organ failure. Paradoxically, sustained inflammation in sepsis may lead to immune suppression, because of which the host is unable to clear the existing infection. Use of agents that suppress the inflammatory response may accelerate host immune suppression, whereas use of traditional antibiotics does not significantly affect inflammation. In this study, we investigated whether lipoxin A4 (LXA4), a specialized, proresolution lipid mediator, could increase neutrophil phagocytic activity as well as reduce bacterial virulence. Using the mouse cecal ligation and puncture (CLP) model of sepsis, the administration of LXA4 (7 μg/kg i.v.) 1 h after surgery increased neutrophil phagocytic ability and Fcγ receptor I (CD64) expression. Ex vivo studies have confirmed that the direct addition of LXA4 to CLP neutrophils increased phagocytic ability but not CD64 expression. LXA4 did not affect neutrophils taken from control mice in which CD64 expression was minimal. Taken together with in vivo data, these results suggest that LXA4 directly augments CD64-mediated neutrophil phagocytic ability but does not directly increase neutrophil CD64 expression. Bacterial communication and virulence is regulated by quorum sensing inducers. In Pseudomonas aeruginosa, virulence is induced with release of various virulence factors, by N-3-oxododecanolyl homoserine lactone binding to the quorum sensing receptor, LasR. We show that LXA4 is an inhibitor of LasR in P. aeruginosa and that it decreases the release of pyocyanin exotoxin. These results suggest that LXA4 has the novel dual properties of increasing host defense and decreasing pathogen virulence by inhibiting quorum sensing.-Wu, B., Capilato, J., Pham, M. P., Walker, J., Spur, B., Rodriguez, A., Perez, L. J., Yin, K. Lipoxin A4 augments host defense in sepsis and reduces Pseudomonas aeruginosa virulence through quorum sensing inhibition.

Lactobacillus rhamnosus GG supplementation during critical windows of gestation influences immune phenotype in Swiss albino mice offspring.

Probiotic supplementation during critical windows of gestation might have a significant influence on the infant's immune phenotype. Swiss albino mice (F0 generation) aged 31 days were supplemented orally with probiotic Lactobacillus rhamnosus GG (LGG); and the supplementation was continued throughout mating, gestation and lactation. The pups (F1 generation) born to them were separated post weaning and received either the same probiotic supplementation as their mothers or were denied supplementation postnatally. Neutrophil phagocytic ability, splenocyte proliferation, immunoglobulins and cytokines were determined in both F0 and F1 pups. In addition, antibody response against hepatitis-B surface antigen (HBsAg) was determined in F1 pups. Probiotic supplementation had no effect on the neutrophil phagocytic ability and splenocyte proliferation index. The serum immunoglobulin G (IgG) and secretory IgA (s-IgA) among the probiotic supplemented group of F0 generation were significantly (P<0.05) higher compared to the controls. Similarly, the mean concentration of interleukin (IL)-10, IL-17 and interferon gamma (IFN-γ) among F0 probiotic group were significantly higher (P<0.05) compared to the control. Prenatal and postnatal probiotic supplementation in F1 pups led to similar results as F0 dams. Prenatal probiotic supplementation in F1 pups led to significantly (P<0.05) higher serum IgG (55.15 ± 1.35 ng/ml) and intestinal s-IgA (77.9 ± 2.86 ng/mg protein) concentration when compared to the control. Similarly, IFN-γ concentration increased (P<0.05) with prenatal probiotic supplementation compared to the control. However, IL-10 and IL-17 concentrations of prenatal probiotic supplemented F1 pups were comparable to the control. As for the antibody response to HBsAg, prenatal probiotic supplementation led to enhanced HBsAg antibody response (471.4 ± 3.97 U/ml) compared to the control. LGG affected the immune regulation and immune responses favourably in mothers and offspring. In addition, some of the beneficial effects of prenatal LGG supplementation extended into postnatal life of the offspring, thus suggesting possible immunoprogramming effect of LGG.

Effects of Lipoxin A4 on antimicrobial actions of neutrophils in sepsis

In sepsis, hyperactivation of neutrophils can lead to tissue injury. Later, neutrophil dysregulation with reduced levels of migration, decreased apoptosis and inadequate phagocytosis may impair the host׳s ability to clear infection. Lipoxin A4 (LXA4) is a pro-resolution lipid mediator which reduces neutrophil migration and inflammatory mediator expression. As neutrophil migration and activation are important in bacterial clearance, the role of LXA4 in regulating neutrophil function for bacterial clearance is unclear. Using the cecal ligation and puncture (CLP) rat model of sepsis, LXA4 given after 1h reduced blood bacterial load at 24h. LXA4 treatment decreased neutrophil migration to the peritoneum but augmented blood neutrophil phagocytic ability and promoted apoptosis without affecting free radical production. In contrast, LXA4 increased peritoneal neutrophil phagocytic ability without affecting apoptosis or free radical production suggesting that in vivo effects of LXA4 were compartment specific. To investigate if LXA4 acted directly on neutrophils, blood and peritoneal leukocytes were taken from CLP rats 1h after surgery and incubated ex vivo with and without LXA4. LXA4 (1nM) increased phagocytosis in blood neutrophils without affecting apoptosis or free radical production. Ex vivo LXA4 had no effect on peritoneal neutrophils which suggests that LXA4 enhanced peritoneal neutrophil phagocytic ability in vivo by an indirect mechanism. The results suggest that LXA4 reduced neutrophil migration, but increased neutrophil bacteria clearing function without excessive free radical production. This phenotype was associated with reduced blood bacteria load.

S46 Phagocytosis By Blood Neutrophils Is Not Attenuated In Patients With Chronic Obstructive Pulmonary Disease

Rationale All COPD phenotypes have airway neutrophilia but,despite this, bacteria associated infections are common, relate to decline and a significant proportion of patients have persistent airway colonisation. This is suggestive of innate immune dysfunction. In vitro studies have shown reduced neutrophil migratory accuracy in COPD (Sapey, Stockley et al . 2011) however, the ability of the neutrophil to contain bacterial infection upon arrival at a site of infection is poorly understood. Literature regarding the phagocytic ability of neutrophils from patients with COPD is conflicting and inconclusive. It is unclear whether responses change depending on the bacterial species present. We hypothesised that neutrophil phagocytosis during COPD is impaired, predisposing patients to increased inflammation and reduced bacterial clearance. Methods Blood neutrophils were isolated from stable-state COPD patients and healthy age-matched controls (HC). Phagocytosis of both opsonised (with 10% pooled COPD serum) and unopsonised pHrodo™-conjugated Staphylococcus aureus bioparticles (SA, n = 20), or E scherichia coli bioparticles (EC, n = 10) and fluorescently labelled disease-relevant bacteria, Haemophilus influenzae (HI, n = 10) and Streptococcus pneumoniae (SP, n = 10) was assessed, at regular intervals over 60 min, using flow-cytometry. Results were confirmed using time-lapse video microscopy. Results Peak phagocytosis was achieved at 60 min for unopsonised bacteria and 30 min for opsonised bacteria. There were no differences in time to peak phagocytosis between bacterial species. Blood neutrophils from patients with COPD and HC displayed similar phagocytic ability, in both percentage of neutrophils with phagocytic activity and the amount of SA, EC, HI or SP ingested (as indicated by MFI) (COPD vs. HC, p > 0.05 for all). This was ubiquitous to both opsonin independent and opsonin-dependant phagocytosis, and was consistent across all time points measured. A typical comparison is shown in figure one, with unopsonised SA data. Conclusions Phagocytic ability of blood neutrophils from patients with COPD to ingest Staphylococcus aureus, Escherichia coli, Streptococcus pneumoniae and Haemophilus influenzae is not altered compared to age-matched healthy controls. This should be replicated in lung neutrophils to assess whether transmigration to the tissues affects function.

Strategies of professional phagocytes in vivo: unlike macrophages, neutrophils engulf only surface-associated microbes

The early control of potentially invading microbes by our immune system primarily depends on its main professional phagocytes - macrophages and neutrophils. Although the different functions of these two cell types have been extensively studied, little is known about their respective contributions to the initial control of invading microorganisms before the onset of adaptive immune responses. The naturally translucent zebrafish larva has recently emerged as a powerful model vertebrate in which to visualise the dynamic interactions between leukocytes and microbes in vivo. Using high-resolution live imaging, we found that whereas macrophages efficiently engulf bacteria from blood or fluid-filled body cavities, neutrophils barely do so. By contrast, neutrophils very efficiently sweep up surface-associated, but not fluid-borne, bacteria. Thus the physical presentation of unopsonised microbes is a crucial determinant of neutrophil phagocytic ability. Neutrophils engulf microbes only as they move over them, in a 'vacuum-cleaner' type of behaviour. This context-dependent nature of phagocytosis by neutrophils should be of particular relevance to human infectious diseases, especially for the early phase of encounter with microbes new to the host.

Upregulation of reactive oxygen species generation and phagocytosis, and increased apoptosis in human neutrophils during severe sepsis and septic shock.

We evaluated neutrophil activation by measuring its phagocytic ability and oxidative burst activity in 16 patients with sepsis and 16 healthy volunteers. We also focused on neutrophil apoptosis as a regulatory mechanism of the inflammatory response. Neutrophil phagocytosis was evaluated by the detection of propidium iodide (PI)-labeled Staphylococcus aureus added to whole blood. Reactive oxygen species (ROS) formation was quantified by measuring the oxidation of 2',7' dichlorofluorescein diacetate (DCFH-DA) at baseline and after cell stimulation with phorbol myristate acetate (PMA), and bacterial cells (killed S. aureus) or products (lipopolysaccharide [LPS] and N-formyl-methionyl-leucyl-phenylalanine [FMLP]). Apoptosis was assessed in neutrophils stained with annexin V and PI. Neutrophil phagocytic ability was increased in patients with sepsis compared with healthy controls (median geometric mean fluorescence intensity [GMFI] was 101.9 and 54.7, respectively; P = 0.05). ROS formation was enhanced in patients with sepsis compared with healthy volunteers at baseline (median GMFI 275.6 and 52.1, respectively; P < 0.001), and after stimulation with S. aureus (median GMFI 2395.8 and 454.9, respectively; P < 0.001), PMA (median GMFI 1120.6 and 307.5, respectively; P = 0.003), FMLP (median GMFI 792.4 and 123.2, respectively; P < 0.001), and LPS (median GMFI 624.8 and 144.8, respectively; P < 0.001). Early neutrophil apoptosis was increased in patients with sepsis compared with healthy volunteers (median 11.3% and 9.1%, respectively; P = 0.03). These data demonstrate that neutrophil function is enhanced in patients with sepsis. Additionally, circulating neutrophils from patients with sepsis presented with increased early apoptosis, which may be consequence of a regulatory mechanism of the inflammatory response.

Functional Decline in Human Neutrophils with Age.

INTRODUCTION. The neutrophil forms the first line of defence against rapidly dividing bacteria and fungi. As humans age they become more susceptible to infection by these microbes (1). We have investigated the neutrophil functions affected by ageing in humans and examined the underlying mechanisms resulting in the age related decline in function. We have observed a reduction in cell surface expression of the Fc receptor CD16, accompanied by a decrease in the phagocytic ability of neutrophils from elderly individuals. In elderly patients with neutrophilia, in which the fraction of blood neutrophils recently released from the bone marrow is increased, CD16 was not significantly increased. These data suggest that in the elderly neutrophils are released from the bone marrow with compromised function, indicative of a defect in progenitor cell production.

Effect of polyclonal immunoglobulins on neutrophil phagocytic capacity and reactive oxygen production in patients with gram-negative septicemia.

The effect of immunoglobulin (Ig) preparations on neutrophil phagocytic ability and oxidative burst in response to Escherichia coli stimulation was analyzed in 14 patients with gram-negative septicemia by an ex vivo whole blood assay using flow cytometry. In patients, neutrophils exhibited a decreased capacity to phagocytize E. coli and generate reactive oxygen products compared to healthy controls (median -68%, P < 0.01). The addition of both 7S-Ig and 19S-Ig enriched preparations in vitro resulted in a dose-dependent increase in neutrophil reactive oxygen production at concentrations of 10 g/l (median +153% and +211%, P < 0.01, respectively) and 20 g/l (median +205% and +282%, P < 0.01, respectively). A decreased neutrophil phagocytic ability was seen in patients with septicemia (median -58%) compared to healthy controls (P < 0.01). Again, the addition of 7S and 19S-Igs enhanced the phagocytic ability in a dose-dependent manner (10 g/l: median +56 and +126%; 20 g/l: median +126% and +165%, P < 0.01 for all). It can be concluded that both polyclonal Igs can increase depressed neutrophil reactive oxygen production and neutrophil phagocytosis in patients with gram-negative septicemia.

Effect of Pentoxifylline In Vitro on Neutrophil Reactive Oxygen Production and Phagocytic Ability Assessed by Flow Cytometry

Neutrophil granulocytes have been described as agents of defence and destruction. The effect of pentoxifylline on the phagocytic ability and generation of reactive oxygen radicals of neutrophils was studied at concentrations of 1, 10 and 100 mg/L. Flow cytometry was used to study phagocytic ability by measuring uptake of fluorescein-labelled bacteria. The generation of reactive oxygen intermediates was estimated by the quantification of the intracellular conversion of dihydrorhodamine 123 to rhodamine 123. In vitro pentoxifylline treatment diminished neutrophil reactive oxygen production (at 10 mg/L -45% and at 100 mg/L -63%; p < 0.001 for both) and reduced neutrophil phagocytic ability (at 100 mg/L -23%; p < 0.05). Both effects were rapidly reversible after plasma exchange. We conclude that pentoxifylline could decrease oxidative tissue damage by neutrophils in septicaemia or after IV granulocyte transfusion.

In vivo effect of the organophosphorus insecticide trichlorphon on immune response of carp ( Cyprinus carpio) : II. Effect of high doses of trichlorphon on nonspecific immune response

The effect of trichlorphon, one of the most widely used organophosphorus insecticides, on the nonspecific immune response in carp ( Cyprinus carpio) was studied. The effect of 20,000 ppm trichlorphon on the immune response was followed for 3 and 56 days after intoxication. The effect of 10,000 ppm trichlorphon on the nonspecific immune response of carp experimentally infected by Pseudomonas alcaligenes and Aeromonas punctata was also examined. Leucocyte number, phagocytic ability of neutrophils, percentage NBT-positive PMN cells, phagocytic index, lysozyme level in serum, and ceruloplasmin activity in plasma were examined on Days 2, 4, 6, 8, 10, 14, 18, 22, and 26 after carp were exposed. After intoxication leukopenia was observed as decreases in phagocytic ability of neutrophils and in phagocytic index. Lysozyme level in serum was also decreased compared to that of control. The percentage of NBT-positive PMN cells decreased when the ceruloplasmin activity in plasma increased in intoxicated fish.

The phagocytic ability of neutrophils and serum lysozyme activity in experimentally infected carp, Cyprinus carpio L.

The phagocytosis of neutrophils and serum lysozyme activity were investigated in carp experimentally infected with Pseudomonas alcaligenes and Aeromonas punctata. The total leucocyte numbers, relative leucocyte counts, nitroblue tetrazolium (NBT) reduction, NBT test rate, lysozyme activity and lysozyme index were examined on days 7, 14 and 21 after injection. On days 7 and 14 there was a significant increase in total leucocyte numbers and serum lysozyme activity, but a decrease in the NBT test rate and lysozyme index. NBT reduction was unchanged compared with the control group. On day 21 the total leucocyte numbers and lysozyme activity had declined and were less than control values, but there was a significant increase of the NBT test rate, NBT reduction and lysozyme index.