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1.
The aim of this study was to evaluate the influence of age and plasma treatment on neutrophil phagocytosis, CD18 expression and serum opsonic capacity in foals in field settings. Microbial infections constitute a large threat in young foals and neutrophil functions are crucial for the defense. Blood samples were obtained from 13 foals at seven time points between the ages of 2 and 56 days and once from 16 adult horses. Six of the foals were treated with adult plasma at the age of 1 week. Neutrophil phagocytosis of yeast after various opsonizations and the expression of complement adhesion receptor CD18 were analysed by flow cytometry. Autologous serum opsonization resulted in 52+/-6.1% phagocytic neutrophils in 2-day-old foals (n = 12), a significantly lower rate than in adult horses (mean 84+/-3.1%; n = 16). In foals, yeast ingestion per neutrophil was also lower than in adults. Opsonic capacity increased with age (p < 0.05), reaching adult levels at 3-4 weeks. An increase in serum opsonic capacity followed plasma treatment (p < 0.05). The phagocytic capacity of foal neutrophils at the time-points studied was equal to or higher than that in the adults, when pooled adult horse serum or anti-yeast IgG was used as opsonin. In foals, serum IgG concentration was negatively correlated to serum opsonic capacity. CD18 receptor expression was higher in neutrophils from foals (<21 days old) than in those from adult horses (p < 0.05). The results indicate that foals are transiently deficient in serum opsonic capacity, which negatively affects their capacity for neutrophil phagocytosis. These changes in serum opsonins, unrelated to IgG, may be important factors in susceptibility to infections in foals.  相似文献   

2.
BACKGROUND: Phagocytic activity of neonatal foals has been reported to be similar to that of adult horses, but serum opsonization capacity develops with age and may be further altered when opsonins are consumed during infection. HYPOTHESIS: Phagocytosis, oxidative burst activity, and serum opsonization capacity in neonatal foals admitted to an intensive care unit are reduced in comparison with control foals. ANIMALS: Blood samples were collected from hospitalized neonatal foals and from control foals. Hospitalized foals were characterized as sick or septic on the basis of a sepsis score and received intravenous plasma transfusion. METHODS: Phagocytosis, oxidative burst activity, and serum opsonization capacity were tested with flow cytometric analysis. Serum immunoglobulin and complement component 3 concentrations were determined with radial immunodiffusion. Serum amyloid A concentration was assayed with a commercially available solid-phase Sandwich ELISA Kit. Data were analyzed with nonparametric and regression methods. Alpha was set at P = .05. RESULTS: Phagocytic functions of septic and sick foals were lower than control foals in the initial phase of the study (P = .01). Opsonization capacity was significantly higher when bacteria were opsonized with serum from septic (P = .029) and sick (P = .006) foals than from control foals on day 1. Opsonization capacity in septic foals was comparable with control foals on days 2 and 5. This effect was not accompanied by an increase in serum complement C3 or immunoglobulin G concentrations independently. CONCLUSIONS AND CLINICAL IMPORTANCE: Our results suggest that phagocytic function could be decreased in hospitalized foals. The synergistic effect of opsonic elements provided by plasma transfusion may sustain opsonization capacity during sepsis.  相似文献   

3.
Opsonization of yeast cells with equine iC3b, C3b, and IgG   总被引：1，自引：0，他引：1  
The main opsonins in serum are antibodies and complement factor C3. The opsonization mechanisms including complement activation and deposition are important in studies of phagocytosis and of mechanisms of microbial immune evasion. The objective of the present study was to monitor the deposition of complement C3 and IgG from equine serum on yeast cells (Saccharomyces cerevisiae) using a flow cytometric immunoassay. Correlations were made between the opsonic coating and phagocytic capacity using equine blood neutrophils. In addition, the bound C3 fragments were characterized by SDS–PAGE and Western blot analyses.

Opsonic coating of yeast with equine C3 and IgG occurred rapidly with detectable levels with as little as 0.75% serum. C3 deposition was a result of complement activation and no passive adsorption was observed. When complement was inactivated, the fluorescence indicating IgG deposition increased 3–6-fold, indicating spatial competition between C3 and IgG at binding.

Opsonization with 1.5% serum led to suboptimal equine neutrophil phagocytosis of yeast cells which was dependent on complement activation by the classical pathway. With ≥6.25% serum, IgG contributed to opsonization and phagocytosis. With 50% serum and more, C3 was deposited also by the alternative pathway. Phagocytosis rates became optimal with 3% serum, and did not increase further with higher serum concentrations. The main form of C3 on the yeast cells was iC3b and the rest was C3b without any detectable breakdown products (C3c or C3dg). The equine complement components are similar in size to the human equivalents.

It may be concluded that opsonization of yeast particles leading to phagocytosis, occurs at very low serum concentrations (1.5%) and that it is dependent on activation of the classical complement pathway at this low opsonic level. This is an important finding for efficient host defense, e.g. extravascular phagocytosis at infection sites.  相似文献   


4.
OBJECTIVE: To evaluate equine IgG as a treatment for kittens with failure of passive transfer of immunity (FPT). ANIMALS: 13 specific pathogen-free queens and their 77 kittens. PROCEDURE: Kittens were randomized at birth into 9 treatment groups. One group contained colostrum-fed (nursing) kittens; the other groups contained colostrum-deprived kittens that were administered supplemental feline or equine IgG PO or SC during the first 12 hours after birth. Blood samples were collected at serial time points from birth to 56 days of age for determination of serum IgG concentrations. The capacity of equine IgG to opsonize bacteria for phagocytosis by feline neutrophils was determined via flow cytometry. RESULTS: Kittens that received feline or equine IgG SC had significantly higher serum IgG concentrations than those of kittens that received the supplements PO. In kittens that were administered supplemental IgG SC, serum IgG concentrations were considered adequate for protection against infection. The half-life of IgG in kittens treated with equine IgG was shorter than that in kittens treated with feline IgG. Feline IgG significantly enhanced the phagocytosis of bacteria by feline neutrophils, but equine IgG did not. CONCLUSIONS AND CLINICAL RELEVANCE: Serum concentrations of equine IgG that are considered protective against infection are easily attained in kittens, but the failure of these antibodies to promote bacterial phagocytosis in vitro suggests that equine IgG may be an inappropriate treatment for FPT in kittens.  相似文献   

5.
Flow cytometric assays were used to compare phagocytic and oxidative burst activity of neutrophils from healthy foals less than 7 days of age with the activity of cells from healthy adult horses. The phagocytosis of Staphylococcus aureus by foal neutrophils was less than that observed for adult neutrophils when autologous serum was used as the source of opsonins in the assay. The use of adult serum did not significantly improve the ability of foal neutrophils to attach bacteria. The oxidative burst activity of foal neutrophils was equivalent to that of adult cells. However, when serum or plasma was incorporated into the oxidative burst assay, foal neutrophils demonstrated greatly reduced autofluorescence and a suppressed response to phorbol myristate acetate (PMA), relative to that demonstrated by adult cells. These results suggest that peripheral blood neutrophils from foals have a reduced ability to phagocytose bacteria relative to that exhibited by adult horse neutrophils and that the oxidative burst activity of foal neutrophils is down-regulated in response to an unidentified serum factor(s). Such changes may contribute to the increased susceptibility of foals to septic disease.  相似文献   

6.
OBJECTIVE: To determine the effects of pasteurization of colostrum on serum lactoferrin concentration and neutrophil oxidative function by comparing values from calves given pasteurized (76 C, 15 minutes) colostrum versus calves given fresh frozen colostrum. ANIMALS: 8 Holstein bull calves were used to study the effects of pasteurization of colostrum on the absorption of lactoferrin and neutrophil oxidative burst. Three additional calves were used to study the effect of exogenous lactoferrin on neutrophil oxidative burst. METHODS: Calves were fed fresh frozen or heat pasteurized colostrum (76 C for 15 minutes) via esophageal feeder within 4 hours of birth. Neutrophils were isolated from whole blood samples. Neutrophil oxidative burst was induced by phorbol ester (300 ng/ml) stimulation of cells (1 X 10(6) cells) at 37 C. Serum lactoferrin concentrations were compared, using immunoblot analysis. Serum IgG concentrations were determined by radial immunoassay. Comparisons were made between the use of the 2 types of colostrum in calves by measuring subsequent serum IgG and lactoferrin concentrations and neutrophil superoxide production. RESULTS: Serum IgG and lactoferrin concentrations increased more in calves receiving fresh frozen colostrum. Neutrophil superoxide production was higher in neutrophils prepared from calves receiving fresh frozen colostrum. Colostral lactoferrin addition to neutrophil incubations resulted in increased oxidative burst. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with calves given fresh frozen colostrum, calves given pasteurized colostrum had decreased serum IgG and lactoferrin concentrations and neutrophil superoxide production 24 hours after administration. These results suggest that pasteurizing bovine colostrum at 76 C for 15 minutes has substantial effects on passive transfer of proteins and neutrophil function.  相似文献   

7.
OBJECTIVE: To evaluate the use of adult cat serum as an immunoglobulin supplement in kittens with failure of passive transfer. DESIGN: Randomized controlled study. ANIMALS: 11 specific pathogen-free queens and their 43 kittens. PROCEDURE: Kittens were removed from the queens at birth, prior to suckling colostrum, and randomly assigned to 1 of 4 groups: colostrum-deprived, colostrum-fed, colostrum-deprived and administration of pooled adult cat serum i.p., and colostrum-deprived and administration of pooled adult serum s.c.. Colostrum-fed kittens were returned to the queen and allowed to suckle normally. Colostrum-deprived kittens were isolated from the queen and fed a kitten milk replacer for 2 days to prevent absorption of colostral IgG. All colostrum-deprived kittens were returned to the queen on day 3. Serum IgG concentrations were measured by radial immunodiffusion in the kittens at birth and 2 days and 1, 2, 4, 6, and 8 weeks after birth. RESULTS: None of the kittens had detectable serum IgG at birth. Both i.p. and s.c. administration of adult cat serum resulted in peak serum IgG concentrations equivalent to those in kittens that suckled normally. Untreated colostrum-deprived kittens did not achieve serum IgG concentrations comparable to those for kittens in the other groups until 6 weeks of age. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that adult cat serum may be used as an immunoglobulin supplement in colostrum-deprived kittens. Although the minimum concentration of IgG necessary to protect kittens from infection is unknown, concentrations achieved were comparable to those in kittens that suckled normally.  相似文献   

8.
The purpose of this study was to clarify whether cats have a colostral and milk phase of lactation differentiated by concentrations of immunoglobulins, and whether colostrum ingestion by newborn kittens is essential for optimal transfer of passive immunity. Milk from specific pathogen-free queens was analyzed for IgG and IgA concentrations from parturition through 6 weeks of lactation. Serum IgG and IgA concentrations from birth through 8 weeks of age were determined for colostrum-fed kittens, colostrum-deprived kittens that were fed a milk replacer, and colostrum-deprived kittens that were fostered onto queens in the milk phase of lactation. The total IgG and IgA concentrations in milk were significantly higher on the day of parturition than on day 7 of lactation, indicating cats do have a colostral phase of lactation. The predominant immunoglobulin in both colostrum and milk was IgG. The serum IgG concentrations in colostrum-deprived kittens fostered on queens in the milk phase of lactation were similar to colostrum-deprived kittens fed a milk replacer, and the concentrations were significantly lower than in colostrum-fed kittens for the first 4 weeks of life. The serum IgA concentrations in both colostrum-deprived groups were significantly lower than colostrum-fed kittens on day 2 after parturition, but were similar thereafter. Colostrum-deprived kittens fostered onto queens in the milk phase of lactation had failure of passive transfer of maternal antibodies. Protective concentrations of immunoglobulins can be restored in kittens with failure of passive transfer of immunity by parenteral administration of adult cat serum, but not by fostering on queens in mid-lactation.  相似文献   

9.
The effect of diapedesis on the phagocytic and oxidative burst activity of polymorphonuclear neutrophil (PMN) was examined, using an in vitro cell culture model consisting of a monolayer of primary mammary epithelial cells. Isolated blood PMN from 10 cows were added to the basal side of the epithelial cell monolayer. Diapedesis was induced by the addition of complement factor C5a to the apical side of the monolayer. PMN phagocytosis of Staphylococcus aureus and oxidative burst were measured before diapedesis on PMN that were non-activated and activated by incubation with C5a and on PMN after diapedesis, using flow cytometry. The percentages of PMN fluorescing due to phagocytosis of S. aureus and oxidative burst were reduced by 21.2 and 14.4%, respectively, after diapedesis. Pre-incubation in the presence of C5a had no effect on percentage PMN fluorescing due to phagocytosis or oxidative burst. The capacity for individual migrated PMN to phagocytose S. aureus and to produce an oxidative burst, as measured by the intensity of fluorescence, decreased by 34.2 and 30.3%. Activation of PMN with C5a increased intensity due to the oxidative burst, but had no effect on intensity due to phagocytosis. These data show that PMN diapedesis across mammary epithelium results in decreased phagocytosis and oxidative burst of the PMN.  相似文献   

10.
OBJECTIVE: To evaluate the effect of plasma transfusion on phagocytosis and oxidative burst activity of peripheral blood neutrophils from healthy and septic equine neonates with sub-optimal passive transfer of maternal immunity. ANIMALS: Nine healthy and seven septic foals with suboptimal passive transfer of maternal immunity (serum IgG < 8 g/L) presented to participating veterinary hospitals for plasma transfusion, and seven healthy foals less than 7 days of age and with circulating IgG concentrations > or = 8 g/L. PROCEDURE: Foals with serum IgG concentrations < 8 g/L were assessed as healthy or septic. Sepsis was recognised by positive bacterial cultures and/or sepsis scores of > or = 11. All foals received between 1 and 3 L of plasma to boost circulating IgG concentrations to > or = 8 g/L. Serum IgG concentrations were determined before and following transfusion by glutaraldehyde coagulation test and confirmed by single radial immunodiffusion assays. Neutrophil phagocytosis and oxidative burst activity were determined before plasma transfusion and at 0 h, 12 h, 24 h, 48 h and 5 d following treatment. Neutrophil function from seven healthy foals less than 7 d of age and with circulating IgG concentrations of > or = 8 g/L was similarly evaluated on a single occasion. RESULTS: Plasma treatment significantly increased circulating IgG concentrations for healthy and septic foals. Oxidative burst activity of neutrophils from septic foals was significantly increased 5 days following treatment, relative to 0 h post treatment. Other differences were not significant but suggested a transient decrease in phagocytosis by neutrophils from healthy foals and increased phagocytosis by neutrophils from septic foals immediately following transfusion. Oxidative burst activity of neutrophils from septic foals tended to be less than that of healthy foals at all sampling times. Serum IgG concentrations were not correlated with neutrophil phagocytosis, but were correlated with oxidative burst activity. CONCLUSIONS: Plasma transfusion did not improve neutrophil function of healthy foals, suggesting that such treatment may be of equivocal benefit for healthy neonates. Conversely, improved neutrophil function was observed following treatment of septic foals, suggesting that plasma transfusion was beneficial for these foals. Oxidative burst activity of neutrophils from septic foals was lower than that of neutrophils from healthy foals and was significantly improved 5 days post treatment, when compared with values obtained immediately following treatment.  相似文献   

11.
Summary

A review is presented of the phagocytosis and intracellular killing of Staphylococcus aureus by polymorphonuclear and mononuclear leukocytes. Recruitment of adequate numbers of leukocytes to the site of infection occurs through the process of chemotaxis. Recognition of invading staphylococci by the phagocytic cells is mediated through bacterial opsonization. Both processess depend upon the activation of the heat‐labile complement system which generates the majority of chemotactic (C5a) and opsonic (C3b) molecules for S. aureus phagocytosis. The key role of peptidoglycan in the cell wall of staphylococci in these events is stressed. Attachment and ingestion of opsonized staphylococci occurs via poorly‐defined receptors for opsonins in the membrane of the leukocyte. The greater phagocytic capacity of neutrophils as compared to monocytes is not reflected in differences in their membrane receptors for staphylococcal opsonins. Once ingested, staphylococci are rapidly destroyed by oxygen‐dependent and oxygen‐independent bactericidal mechanisms of the phagocytes. Small numbers of S. aureus may survive within the leukocyte. Special attention is focused on the numerous ways S. aureus is able to hinder, evade, and directly damage the phagocytic defense mechanisms of the host.  相似文献   

12.
Seventeen newborn lambs were fed with untreated colostrum (group A) and 18 lambs were fed with colostrum treated by heat (56 °C, 30 min) (group B). Blood samples were obtained at seven time points from day 0 to 38 of life. Clinical status and body weight were recorded and serum protein fractions and IgG levels were determined in blood. Phagocytosis of neutrophils from the lambs and opsonic capacity of their serum were examined using a flow cytometry method. As an indicator of in vivo cellular immunity, reactions to intradermal injection of phytohemagglutinin (PHA) were examined at 8 and 16 days of age. There were no clinical signs of disease and no significant differences in body weight between groups. Lambs from group B had lower total protein initially and lower γ-globulin and IgG levels until day 32 compared to lambs from group A (P < 0.01). Heat treatment of colostrum had no significant effect on serum opsonic capacity or phagocytosis by neutrophils and these functions increased with age. However, responses to PHA in lambs from group B were lower (P < 0.01) than group A at day 8 of life, but not at day 16, suggesting that cellular immunity was affected by the treatment of colostrum. These results showed that colostrum treated by heat impaired cellular and IgG levels in lambs, but not phagocytic function. However, these changes did not affect the health or performance of the lambs.  相似文献   

13.
Two of the most commonly isolated foal pathogens are Escherichia coli and Actinobacillus equuli. The hypothesis tested in this study was that young foals carry a lower opsonic capacity for these bacteria compared to adult horses. A flow-cytometric method for the phagocytosis of these by equine neutrophils was established. The opsonic capacity of serum from healthy foals from birth to age 6 weeks was evaluated and related to the concentrations of IgGa and IgGb. Phagocytosis of yeast was used as a control. Serum was required for phagocytosis, with higher concentrations for E. coli than for A. equuli. Ingestion of colostrum led to a significantly higher serum opsonic capacity. After that, there was no consistent age-related trend for opsonic capacity for the different microbes. Foal serum showed similar or higher opsonisation of E. coli and A. equuli compared to serum from mature individuals. During the studied period, the predominance among IgG subisotypes switched from IgGb to IgGa. Although the overall correlation between concentrations of IgG subisotypes and serum opsonic capacity was poor, sera with IgGb levels below 1.9 mg/ml induced lower opsonisation of E. coli and yeast, but not of A. equuli. Complement activation was important for opsonisation of all tested microbes. The results of this study are significant to the understanding of a key immunological facet in the pathophysiology of equine neonatal septicaemia in clinical practice.  相似文献   

14.
OBJECTIVES: To evaluate effects of proinflammatory mediators on phagocytosis and killing of Staphylococcus aureus, the oxidative burst (OB), and expression of receptors for opsonins by bovine neutrophils. SAMPLE POPULATION: Neutrophils from 10 cattle. PROCEDURE: Neutrophils were primed with recombinant bovine tumor necrosis factor-alpha (TNF-alpha) or the des-arginine derivative of bovine C5a (C5a(desArg)) and mixed with S aureus. Phagocytosis and OB were measured by use of flow cytometry. Rate of phagocytosis and intracellular killing were evaluated. Expression of receptors for immunoglobulins and the C3bi fragment of complement were estimated by use of flow cytometry. RESULTS: Priming of neutrophils by TNF-alpha improved phagocytosis of S aureus with a concentration-dependent effect. Phagocytosis of preopsonized washed bacteria was increased by activation of neutrophils with C5a(desArg). Phagocytosis was optimal when neutrophils primed with TNF-alpha were activated with C5a(desArg). The OB of phagocytizing neutrophils was highest when TNF-alpha and C5a(desArg) were used in combination. Bactericidal activity of neutrophils was stimulated by priming with TNF-alpha or C5a(desArg). Binding of bovine IgM or IgG2 to bovine neutrophils was not stimulated byTNF-alpha, C5a(desArg), or both, and aggregated IgG1 did not bind to neutrophils regardless of their activation state. Both TNF-alpha and C5a(desArg) increased expression of beta2 integrins (CD18), with the highest expression when they were used in combination. CONCLUSIONS AND CLINICAL RELEVANCE: The mediators TNF-alpha and C5a(desArg) stimulated phagocytic killing by neutrophils and potentiated each other when used at suboptimal concentrations. Bovine neutrophils have enhanced bactericidal activities at inflammatory sites when TNF-alpha, C5a(desArg), or both are produced locally.  相似文献   

15.
The putative immunosuppressive effect of PRRS virus (PRRSV) on innate immune responses was studied in piglets infected in utero with PRRSV. Phagocytosis and oxidative burst capacities in 2-, 4- and 6-week-old in utero infected piglets were investigated and compared with age-matched control piglets. Phagocytic capacity of blood monocytes against Salmonella bacteria was investigated by flow cytometry. Oxidative burst in blood monocytes and in alveolar lung macrophages was investigated by luminol- and lucigenin-enhanced chemiluminescence, respectively. Decreased phagocytosis against Salmonella was found in blood monocytes from 4- and 6-week-old infected piglets compared to controls. In contrast, 2-week-old infected piglets showed phagocytic responses comparable to age matched control piglets. While oxidative burst capacity was increased in blood (PBMC) from in utero PRRSV infected piglets, the oxidative burst capacity of alveolar lung macrophages was decreased, especially in 2- and 4-week-old piglets, compared to age-matched control piglets. The present results indicate that in utero infection with PRRSV inhibits phagocytosis against Salmonella in blood monocytes as well as the oxidative burst capacity of alveolar macrophages. These observations indicate that PRRSV in utero infection induces at state of immunosuppression in piglets paving the way for enhanced secondary infections.  相似文献   

16.
Decreased neutrophil function following administration of chemotherapy has been reported in dogs with lymphoma. The first objective of our study was to determine if neutrophil oxidative burst and phagocytic activity are affected by chemotherapy 7 to 10 days following initiation of treatment in dogs with lymphoma and non-lymphoma malignancies. The second objective was to determine if there is a correlation between neutrophil numbers and neutrophil function before or after initiation of chemotherapy. Flow cytometric assessment of neutrophil oxidative burst and phagocytosis following stimulation with Escherichia coli was performed in 9 dogs diagnosed with lymphoma and 17 non-lymphoma tumor-bearing dogs pre- and post-chemotherapy, as well as 14 tumor-free control dogs. Spearman rank correlation was performed to determine if blood neutrophil numbers and neutrophil function were significantly correlated. Lymphoma patients showed significantly reduced percentage neutrophil oxidative burst post-chemotherapy compared to healthy controls as well as compared to pre-chemotherapy values (P = 0.0022 and P = 0.0020, respectively). Lymphoma patients also exhibited significantly reduced neutrophil phagocytosis activity post-chemotherapy compared to controls and pre-chemotherapy values (P = 0.0016 and P = 0.014, respectively). Dogs with non-lymphoma malignancies also showed a significant decrease in both percentage oxidative burst and phagocytosis post-chemotherapy compared to pre-chemotherapy values (P = 0.00040 and P = 0.029, respectively). Neutrophil numbers and function were not significantly correlated. The results of the study suggest that chemotherapeutic treatment decreases neutrophil oxidative burst and phagocytic activity 7 to 10 days post-treatment in dogs with various malignancies. Furthermore, neutrophil numbers cannot be used to predict neutrophil function.  相似文献   

17.
An enzyme-linked immunosorbent assay (ELISA) demonstrated the presence of naturally acquired antibodies against Streptococcus agalactiae in normal bovine serum (NBS). In milk wheys, ELISA values were much lower than in sera. Pre-colostral calf serum (PCS) was shown to lack antibodies to type II and III S. agalactiae. The opsonic requirements of 10 human and 10 bovine strains were investigated by evaluating the phagocytosis-induced reduction of the incorporation of radiolabeled thymidine by streptococci. Antibodies present in NBS were required for the efficient ingestion of both human and bovine isolates type II by bovine granulocytes. Three out of five type III bovine isolates were opsonized in the absence of specific antibodies (opsonization by PCS) and type II and III bovine isolates did not require complement opsonization. By contrast, inactivation of complement reduced phagocytosis of human isolates and only one type III strain of human origin was opsonized by PCS. These findings suggest that human isolates had higher opsonic requirements. The phagocytic killing of 6 type III strains (5 mastitis isolates and the reference typing strain) was investigated. Opsonization by normal serum enabled bovine blood granulocytes to ingest and kill S. agalactiae. Nevertheless, greater than or equal to 35% of bacteria remained viable at the end of the phagocytosis incubation in 10% NBS. Heat treatment of serum decreased the efficacy of killing for only 3 of the 6 tested strains. An IgG2 fraction of normal adult bovine serum promoted active ingestion, which was still increased in the presence of PCS. Normal wheys displayed large variations in their ability to promote ingestion of S. agalactiae by blood granulocytes. The promoting effect was systematically less than that of serum from the same cow, and this can be related to the lower ELISA values found in wheys.  相似文献   

18.
The aim of this study was to evaluate the immune responses in hybrid tilapia (Nile tilapia Oreochromis niloticus x Mozambique tilapia O. mossambicus) and Japanese eels Anguilla japonica after treatment with five glycans: barley, krestin, MacroGard, scleroglucan, and zymosan. The effects of the glycans on the innate immune responses of the fish were investigated using the phagocytic index (PI), lysozyme activity, complement opsonization, and activation assay. The results of the lysozyme assay demonstrated that the lysozyme activities increased after treatment with glycans. Moreover, based on the PI, treatment with each of the five glycans resulted in increased phagocytic activities in anterior kidney and peripheral blood phagocytes in both tilapia and Japanese eels. The opsonic effect of complement on phagocytosis in tilapia and Japanese eels were investigated using baker's yeast, which served as the activator in the classical complement pathway (CCP) and in the alternative complement pathway (ACP). Tilapia and Japanese eel sera that were treated with glycans greatly enhanced phagocytosis. The classical pathway--hemolytic complement titer (CH50) of Japanese eels treated with glycans was slightly increased in vitro and in vivo. While glycan treatment enhanced the CCP of both species in vitro and in vivo, the alternative pathway-hemolytic complement titer (ACH50) was only increased in vitro and in vivo in glycan-treated tilapia. Thus, it follows that the ACP must have been activated in tilapia treated with glycans. However, in Japanese eels, the ACH50 of the ACP activation assay was undetected in vitro or in vivo due to possible unknown factors in the Japanese eel serum that caused lysis of the rabbit red blood cells. Our study investigated the effects of glycans used to enhance phagocytosis and activate both of the complement pathways involved in stimulating the innate immune responses of Japanese eels and tilapia.  相似文献   

19.
Bovine milk contains various immunoreactive components, and the activation of polymorphonuclear leukocytes (PMNLs) function in breast-fed infants has been reported. In this study, the effect of milk on the oxidative burst of bovine PMNLs was investigated in vitro. When PMNLs were incubated with 0.1% colostrum or normal milk, the oxidative burst induced by serum-opsonized Staphylococcus aureus was enhanced, and the enhancement declined dose-dependently. The enhancement of the oxidative burst by milk was not due to opsonins but the priming activities. Also, the phorbol 12-myristate 13-acetate (PMA)-induced oxidative burst increased after incubation with 0.1% colostrum, but the colostral enhancement of the oxidative burst was unaffected by the incubation time. These results suggest that bovine milk contains oxidative burst promoting factor(s).  相似文献   

20.
Neutrophils and alveolar macrophages are essential defence mechanisms against bacterial infection of the lung. The purpose of this study was to evaluate the variability of a panel of neutrophil and alveolar macrophage function assays in swine, and to determine if the function of these leukocytes differed at various stages of production. Measured neutrophil functions included chemotaxis, phagocytosis, oxidative burst, and degranulation. Phagocytosis and oxidative burst were measured in alveolar macrophages isolated from bronchoalveolar lavage fluid (BALF). Both neutrophil and alveolar macrophage functions were highly variable from day-to-day and between pigs. Individual pigs did not have consistently high or low neutrophil and macrophage responses over time when compared to their cohorts. Older grower-finisher pigs had significantly greater neutrophil oxidative burst responses than younger suckling and weaner pigs (P < 0.001). Similarly, alveolar macrophages from suckling and early weaner pigs less than 40 days of age had significantly lower oxidative burst responses than those from older pigs (P = 0.02). Age-related variation in phagocytosis, chemotaxis, or granule secretion were not detected. These results establish baseline data for individual and age-related variation in swine leukocyte function, and form a basis for further evaluation of the contribution of non-infectious factors to development of the porcine respiratory disease complex.  相似文献   

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