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PubMed1985

Chemiluminescence of bovine alveolar macrophages as an indicator of developing immunity in calves vaccinated with aromatic-dependent Salmonella.

Chemiluminescence of bovine alveolar macrophages was used to study the development of opsonins in calves vaccinated parenterally with live aromatic-dependent strains of either S. dublin or S. typhimurium. These calves responded by producing Salmonella-specific opsonins detected by increased chemiluminescent responses, and were able to survive oral challenge with live virulent organisms of either serotype. Non-vaccinated calves of the same age lacked Salmonella-specific opsonins and were not able to survive challenge. Thus it was concluded that the ability to produce opsonins is among the immunological responses that are associated with protection against salmonellosis in calves. Antigenic similarities between S. dublin and S. typhimurium were shown by the ability of either organism to absorb significant amounts of opsonic capacity from the sera of calves vaccinated with either of the two vaccines. These antigenic similarities are thought to explain in part the ability of either vaccine to protect against challenge with either the homologous or heterologous Salmonella serotype.

Animals↗
PubMed2006

Phosphatidylserine recognition by phagocytes: a view to a kill.

The redistribution of phosphatidylserine (PS) to the external surface of the plasma membrane is a key element of apoptotic cell recognition and is a molecular cue that dying cells should be engulfed. Phagocytes interact with PS on apoptotic cells through either the PS receptor or secreted bridging proteins called opsonins. The study of two secreted PS opsonins, MFG-E8 and Gas6 and their receptors alphavbeta5 (and alphavbeta3) integrin and Mer tyrosine kinase, respectively, have provided insights into the temporal and spatial aspects of Rac1 activation following the recognition and internalization of apoptotic cells. Disruption of PS opsonins and their signaling pathways often manifest conditions of inflammation and autoimmune disease. Here, we review recent studies involving PS opsonins, their receptors and their role in the phagocytosis of apoptotic cells.

Adaptor Proteins, Signal Transducing↗
PubMed1988

Effects of bovine colostrum, foal serum immunoglobulin concentration and intravenous plasma transfusion on chemiluminescence response of foal neutrophils.

The effects of bovine colostrum, absorption of equine colostral immunoglobulins and age on phagocytic and serum opsonizing activity of nine clinically healthy foals were examined. Cells and serum were collected prior to suckling and at 7, 14 and 28 days of age. Seven foals had serum IgG concentrations greater than 600 mg/dl whereas two foals had less than 350 mg of IgG/dl. Phagocytic and serum opsonic activity of eight clinically ill foals with less than 400 mg of IgG/dl of serum were also examined before and after plasma transfusion. Phagocytic and serum opsonizing activities were evaluated by an assay for chemiluminescence (CL) after addition of opsonized streptococci. Results showed that bovine colostrum stimulated CL of foal neutrophils. Preliminary characterization of opsonins in bovine colostrum by ammonium sulphate fractionating and heat inactivation indicated that opsonins generating CL were mainly associated with immunoglobulin G. Chemiluminescence generated by foal neutrophils varied with age with foal neutrophils collected at day 14 producing more CL than adult neutrophils (P less than 0.05). Foal serum opsonizing activity was similar to adult opsonizing activity if serum IgG concentrations were greater than 600 mg/dl but it was less if IgG concentration was less than 350 mg/dl (P less than 0.05). Chemiluminescence generated by foal and adult neutrophils was higher when post-transfusion foal serum was used as the source of opsonin than when pre-transfusion foal serum was used (P less than 0.05). When adult serum was the opsonin, chemiluminescence of foal neutrophils collected before and after plasma transfusion did not differ. The increase in CL following plasma transfusion was probably due to an increase in serum opsonizing activity.

Aging↗
PubMed1978

Evidence for quantitative variability of bacterial opsonic requirements.

We studied human serum opsonins by using combinations of heat inactivation and chelation to inhibit complement, adsorption to remove antibody, and trypan blue to inactivate the C3 receptor of human polymorphonuclear leukocytes. Streptococcus pneumoniae, serotype 25, required both complement and immunoglobulin for opsonization, even though that strain activated the alternative complement pathway. Both strains of Escherichia coli required antibody and complement, but varied in the degree of dependence on the C3 opsonin, since trypan blue moderately inhibited the killing of E. coli-1 and markedly inhibited the killing of E. coli-2. Serratia marcescens was opsonized in heat-inactivated serum (limited complement) or serum absorbed at 0 degrees C with S. marcescens (limited antibody), but depended on the C3 receptor in absorbed serum. S. marcescens activated the alternative pathway. Thus, opsonic requirements varied with the availability of opsonins. Requirements for bacterial opsonization vary with species and strains within species, perhaps reflecting quantitative relationships among alternative and classical pathway activation of C3, efficiency of adsorption of C3 or immunoglobulin G to bacterial surfaces, and efficiency of attachment of these ligands to polymorphonuclear leukocyte receptors. Furthermore, although not always sufficient for opsonization, the C3 opsonin (activated through either the classical or alternative pathway) appears necessary for effective phagocytosis and killing of all strains studied.

Antibodies, Bacterial↗
PubMed1978

Phagocytosis of Cryptococcus neoformans by normal and thioglycolate-activated macrophages.

Phagocytosis of Cryptococcus neoformans by normal and thioglycolate-activated mouse peritoneal macrophages was studied. Thioglycolate-activated macrophages exhibited a lower percent phagocytosis than did normal macrophages. Differences in phagocytosis could not be attributed to differences in macrophage viability, minor variations in the concentration of adherent macrophages, or a general depression in activated macrophage phagocytosis. Thioglycolate-activated macrophages required heat-labile opsonins for optimal phagocytosis of non-encapsulated cryptococci, whereas nonactivated macrophages did not require heat-labile opsonins for phagocytosis of the yeast. Both types of macrophages exhibited similar sensitivity to the phagocytosis-inhibiting properties of cryptococcal polysaccharide. The results show that depletion of heat-labile opsonins from serum or inactivation of yeast-bound, heat-labile opsonins by polysaccharide cannot account for the phagocytosis-inhibiting properties of cryptococcal polysaccharide.

Animals↗
PubMed1986

Chemiluminescent response of polymorphonuclear leukocytes to Streptococcus pneumoniae and Haemophilus influenzae in suspension and adhered to glass.

We measured the luminol- and lucigenin-enhanced chemiluminescent response of human polymorphonuclear leukocytes (PMN) stimulated by various strains of Streptococcus pneumoniae and Haemophilus influenzae. In the absence of opsonin, phagocytosis of either bacterial species elicited good PMN response when the bacteria were adhered to a surface but minimal PMN response when they were in suspension. When 10% pooled human serum was used as a source of opsonin, a moderate to excellent chemiluminescent PMN response was elicited during phagocytosis of opsonized bacteria both in suspension and adhered to surface. We conclude that opsonin significantly enhances PMN chemiluminescence when a suspension-type assay is used and that opsonin-independent mechanisms play a significant role in the chemiluminescent response of PMN during phagocytosis of adherent bacteria.

Acridines↗
PubMed1986

Opsonic requirements for hepatic clearance of pneumococci.

An in situ isolated, perfused rat liver system was used to evaluate various opsonins for hepatic trapping and killing of encapsulated, virulent, type 3 pneumococci. Pneumococci were rapidly trapped in the liver in the presence of all potential opsonins including Hanks balanced salt solution with added colloid. However, with some of the potential opsonins the organisms remained viable and could be recovered from the liver. With others there was killing of pneumococci. The combination of rat antibody and complement was effective as an opsonin and produced about the same degree of killing as the same human components. When tested separately killing was not promoted by rat complement, human complement, or human antibody. However, when ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-Mg2+ was added to block the classical pathway and preserve the alternative pathway there was significant pneumococcal killing which may have been complement mediated or due to an adverse effect of ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid-Mg2+ on the organisms. Fibronectin and C-reactive protein reduced the number of surviving microorganisms, although the change was not significant. Immunoglobulin G (IgG)-IgM, IgG, or IgM with complement, and antibody + the classical complement pathway, significantly reduced survival of the organisms. The best killing occurred with antibody plus complement plus fibronectin, which reduced mean survival to 24% during the 1-h perfusion.

Animals↗
PubMed1976

Humoral deficiency and reticuloendothelial depression after traumatic shock.

Circulating opsonin levels and reticuloendothelial (RE) phagocytic activity were investigated in anesthetized rats subjected to Noble-Collip drum (NCD) trauma. Reticuloendothelial function was assessed by colloid clearance kinetics and circulating opsonin levels by in vitro tissue slice bioassay. After sublethal shock, both hepatic RE phagocytosis and plasma opsonic activity were significantly (P less than 0.001) depressed in the 0.5- to 6-h posttrauma period. Pulmonary and bone marrow localization of the blood-borne test microparticles significantly (P less than 0.05) increased during hepatic RES depression. Hepatic RE cells from animals during the interval of posttraumatic in vivo phagocytic depression exhibited normal phagocytosis when incubated in normal pretrauma plasma and decreased phagocytic activity when incubated in posttrauma plasma. After sublethal shock, restoration or opsonin levels by 24 h after shock resulted in hepatic RE recovery. Plasma opsonin levels declined in direct relationship to the degree of trauma. Progressive hepatic RE failure was correlated with the progressive decline in circulating plasma opsonic activity. The findings indicate that opsonic depletion may be involved in the etiology of hepatic reticuloendothelial depression after traumatic shock.

Animals↗
PubMed1982

Interactions between human neutrophils and vaccinia virus: induction of oxidative metabolism and virus inactivation.

The possible role of human neutrophils (PMN) as direct effector cells against free live virus particles was tested in vitro. Oxygen consumption, production of chemiluminescence and "virus killing" by PMNs was examined during and after incubation of cells and live or dead vaccinia virus with and without specific antibody. Oxygen consumption and chemiluminescence production occurred with unopsonized live but not with inactivated virus and was greatly enhanced with opsonization. Virus titers were determined in PMN-free supernatant and freeze-thawed cell pellet fractions after 15 min incubation. Reduction in titer from virus control was seen in supernatant fractions with and without opsonins, but in the cell fraction only with opsonins; the degree of reduction with opsonins was directly related to the opsonin source. PMNs from a patient with chronic granulomatous disease did not inhibit virus replication. These data suggest an active role for human PMNs in the genesis of and defense against virus infections and indicate areas for further investigation.

Antibodies, Viral↗
PubMed1989

[Humoral and cellular changes of non-specific immune response following severe trauma].

The influence of trauma and hemorrhagic shock on the non-specific immune system has been pointed out in various experimental studies. Other investigations have also been able to find a relationship between these changes and a higher incidence of post-traumatic complications in the form of organ failure. Our aim was to demonstrate the potential changes in the cellular defense system in a clinical study on multiple trauma patients. The polymorphonuclear leukocytes (PMNL) are the main representative of the mobile, non-specific immune system. Our study revealed a significant deterioration of PMNL function after trauma. The metabolic activity and phagocytic function were mainly affected by a decrease in the concentration of so-called "opsonins." The opsonins are important for the identification and engulfment of debris (necrosis, fat emboli and thrombi) and bacterial substances (endotoxin). Next to the opsonin level, a change in the receptor configuration is important for phagocytosis. However, we could not find any substantial evidence of surface receptor alteration. The reticuloendothelial cells (RES), a stationary phagocytic system, also showed a significant reduction in clearance function in these polytraumatized patients. Similar to PMNL, these disturbances were based on the reduction of the opsonine concentration. We were able to demonstrate a significant disturbance in immune function in multiple trauma patients with post-traumatic complications compared to patients with a normal clinical course after injury. Disturbances in the PMNL function (seen after 4 days) were found to appear after the RES disturbances. Systemic interaction between these two phagocytic systems cannot be excluded and further investigation is therefore required.

Adolescent↗
PubMed1989

[Plasma fibronectin in surgical patients].

Plasma fibronectin (PFN) was measured to clarify the role in patients who underwent major surgery. There was no statistical difference between male and female, benign and malignant disease, or more than 60 years old and less. Compared to the preoperative values of PFN, the postoperative ones showed significant decrease immediately after operation, this decrease was attributed to massive bleeding and prolonged surgical procedure. In contrast to the previous papers reporting as an opsonin, no such results were obtained. However, there was close relationship between PFN and antithrombin III, alpha 2-plasmin inhibitor, factor XIII, retinol binding protein and transferrin, which represent hemostasis, fibrinolytic system and nutritional status, respectively. To determine whether PFN acts as an opsonin, heparin (opsonin cofactor) was given to Wistar rats in various conditions. There was no significant difference between PFN in those rats and in controls. These results indicate that postoperative PFN is a good parameter of glycoprotein in hemostasis, fibrinolytic system, and rapid turnover protein, not of an opsonin.

Adult↗
PubMed1984

[Radionuclide study of reticuloendothelial system function].

The authors propose a new method for the interpretation of the measurement data obtained during radionuclide investigations of the function of the reticuloendothelial system (RES). This method is upon the concept of a considerable effect of the blood opsonizing factor on the transport of i.v. injected radioactive colloid in the body. A non-linear compartmental model was developed that describes the binding of colloid particles with opsonins in the vascular bed followed by absorption of the particles of the colloid-opsonin complex by RES cells. The identification of the parameters of the non-linear model by the results of dynamic scintigraphy of the heart and liver makes it possible to explain some phenomena in the measurement data and to assess the relative amount of opsonins in the blood and RES phagocytic activity as a whole and its constituents. It was shown in particular in the studies on patients with hepatocirrhosis that the amount of opsonins in the blood remains almost the same as compared to the normal one whereas the phagocytic activity of RES on the whole, hepatic stellate cells and RES extrahepatic cells decreases significantly.

Colloids↗
PubMed2005

Adhesion and ingestion activities of fish phagocytes induced by bacterium Aeromonas salmonicida can be distinguished and directly measured from highly diluted whole blood of fish.

The phagocytes of fish play an important role in innate host defense against bacterial infection, and participate in various immunoregulatory processes. Here, we investigated the effects of various opsonins in the ingestion and adhesion processes by examining respiratory burst (RB) activity in blood and head kidney (HK) fish phagocytes. RB activity was induced in rainbow trout phagocytes with the bacterium Aeromonas salmonicida (strain MT004) in the presence of various opsonins [purified antibodies (Ab), immune serum (IS), normal serum (NS) and heat-inactivated immune serum (HI-IS)], and measured in terms of luminol-amplified chemiluminescence (CL) emission at 20 degrees C for 210 min. The RB activity of blood phagocytes was measured directly from highly diluted whole blood and compared to that observed in isolated head kidney (HK) phagocytes measured under similar conditions. In addition, the extracellular RB activity of adhesion (extracellular degranulation) and the intracellular RB activity of ingestion were distinguished through their inhibition by gelatin and cytochalasin D. Our results showed that the first CL peak appeared within 50 min, and decreased or vanished when gelatin was added to the reaction or when the active complement was destroyed by heating. The second CL peak appeared after 50 min, depending on the utilized opsonin, and vanished when cytochalasin D was added to the reaction. Our results indicate that adhesion and ingestion compete for consumption of reactive oxygen intermediates. Specific IgM without an active complement was a relatively inefficient opsonin, whereas specific IgM with an active complement increased the magnitude of ingestion-mediated RB activity and accelerated the ingestion of target bacteria. Taken together, these results indicate that adhesion and ingestion responses competed for limited phagocyte resources and that the bacterial uptake by blood phagocytes can be measured directly from highly diluted blood.

Aeromonas salmonicida↗
PubMed1999

Interaction of polystyrene microspheres with liver cells: roles of membrane receptors and serum proteins.

Our previous studies have demonstrated that serum would play an important role in the hepatic disposition of polystyrene microspheres (MS) and that complement C3 should be involved as the serum opsonin. In this study, we tried to identify the entity of other serum opsonins and dysopsonin for the hepatic uptake of MSs with particle sizes of 50 nm (MS-50) and 500 nm (MS-500) by isolated liver perfusion studies using a recirculation procedure in rats. Pretreatment of the liver by trypsin significantly suppressed the serum-dependent hepatic uptake of both MSs, suggesting that some protein components on the cell surface should be necessary for the serum-dependent phagocytosis of MSs. Pretreatment of the serum by the anti-fibronectin antibody resulted in a significant reduction in the hepatic disposition of MS-500 (49% of control), suggesting that fibronectin should also work as the opsonin for the hepatic uptake of MS-500. The hepatic disposition of both MSs in the presence of serum was inhibited by the addition of N-acetylgalactosamine into the perfusate, suggesting the possible involvement of lectin in the serum-dependent hepatic uptake of MSs. Furthermore, a more intensive hepatic disposition of MSs was observed in the presence of plasma compared with that in the presence of serum in the perfusate, suggesting the possible involvement of blood coagulation factors, such as fibrinogen, as the opsonin in the hepatic disposition of MSs.

Animals↗
PubMed1994

Role of oxygen in phagocyte microbicidal action.

Immune information in the form of inflammatory mediators directs phagocyte locomotion and increases expression of opsonin receptors such that contact with an opsonized microbe results in receptor ligation and activation of microbicidal metabolism. Carbohydrate dehydrogenation and O2 consumption feed reactions that effectively lower the spin quantum number (S) of O2 from 1 to 1/2 and finally to 0. Oxidase-catalyzed univalent reduction of O2 (S = 1; triplet multiplicity) yields hydrodioxylic acid (HO2) and its conjugate base superoxide, O2- (S = 1/2; doublet multiplicity). Acid or enzymatic disproportionation of superoxide yields H2O2 (S = 0; singlet multiplicity). Haloperoxidase catalyzes H2O2-dependent oxidation of Cl- yielding HOCl (S = 0), and reaction of HOCl with H2O2 yields singlet molecular oxygen, 1O2 (S = 0; singlet multiplicity). The Wigner spin conservation rule restricts direct reaction of S = 1 O2 with S = 0 organic molecules. Lowering the S of O2 overcomes this spin restriction and allows microbicidal combustion. High exergonicity dioxygenation reactions yield electronically excited carbonyl products that relax by photon emission, i.e., phagocyte luminescence. Addition of high quantum yield substrates susceptible to spin allowed dioxygenation, i.e., chemiluminigenic substrates, greatly increases detection sensitivity and defines the nature of the oxygenating agent. Measurement of luminescence allows high sensitivity, real-time, and substrate-specific differential analysis of phagocyte dioxygenating activities. Under assay conditions where immune mediator and opsonin exposure are controlled, luminescence analysis of the initial phase of opsonin-stimulated oxygenation activity allows functional assessment of the opsonin receptor expression per circulating phagocyte and can be used to gauge the in vivo state of immune activation.

Animals↗
PubMed1985

[Plasma fibronectin level in patients with depression of hematopoiesis].

Plasma fibronectin is regarded to play an important part in a decrease of the resistance to infections. To specify the role of fibronectin in the pathogenesis of infectious complications in patients with depressions of hemopoiesis, the content of this opsonin was measured by ELISA in 113 patients with different patterns of hemoblastoses, lymphoproliferative diseases and with an aplastic syndrome. In 42 patients, the concentration of opsonin was measured in the presence of the superimposed infection of varying gravity. The fibronectin content was examined in 39 patients before, during and after completion of the cytostatic polychemotherapy. It turned out that in patients with paraproteinemic hemoblastoses, lymphogranulomatosis, aplastic anemia, chronic lympholeukemia, acute lympho- and myelo(mono)blastic leukemias, cyclic neutropenia, chronic myelosis and hematosarcomas, the concentration of fibronectin remained normal in the absence of infections. The computation of the linear correlation ratio did not reveal any association between the opsonin level and the concentration of neoplastic elements in the peripheral blood. Repeated measurements of the fibronectin level in patients whose underlying disease ran its course in association with marked neoplastic fever failed to detect any deficiency of the glycoprotein. The lowering of the fibronectin level was recorded in patients with a grave concomitant infection of the type of sepsis, necrotic enteropathy and lobar pneumonia. The degree of opsonin deficiency correlated with the patients' disease gravity. Prolonged reduction in the blood fibronectin level was of unfavourable prognostic importance. Cytostatic polychemotherapy, myelotoxic agranulocytosis as well as infectious complications of low gravity did not influence the concentration of fibronectin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Changes in phagocyte activity in patients with ischaemic stroke.

The activity of peripheral phagocytes to generate reactive oxygen species (ROS) was studied in healthy individuals and patients with ischaemic stroke. The aim was to clarify the relationship between phagocyte activity, the time elapsed after the onset of disease and stroke severity. The total and extracellular production of ROS were evaluated by luminol chemiluminescence. Simultaneously the plasma oxidant activity was determined. When stimulated by opsonized zymosan, phagocytes in patients with stroke (regardless of its severity) showed fast activation. The total ROS generation increased over time in all stroke cases studied. However, the extracellular ROS generation was found to be greater in patients with severe stroke than in those with mild neurological deficiency. When stimulated by formyl-methionyl-leucyl-phenylalanine, the total oxidative phagocyte capacity (regardless of stroke severity) increased over time, but there was no change in the amount of extracellularly generated ROS. In patients with stroke the oxidant activity of plasma was enhanced. We conclude that circulating phagocytes in patients with ischaemic stroke are primed for enhanced ROS production by opsonin receptor-mediated stimulation and for increased secretion of myeloperoxidase by opsonin receptor-independent stimulation. The enhanced extracellular generation of ROS through opsonin receptor-dependent stimulation may be considered an oxidative stress biomarker in cerebral ischaemia.

Aged↗
PubMed2004

Mini-review: A pivotal role for innate immunity in the clearance of apoptotic cells.

Apoptotic cells can be recognized and taken up by both macrophages and dendritic cells. Phagocytosis of apoptotic cells generally leads to active suppression of cytokine production by professional phagocytes. This is different from the response towards cells that die by necrosis, which induce a pro-inflammatory cytokine profile. Uptake of apoptotic cells involves a large number of receptors and opsonins, which bind to cellular ligands exposed during the various stages of apoptotic cell death. Among the opsonins of apoptotic cells, complement factors, including C1q, and complement-activating members of the pentraxin family play an important role. This is indicated by in vitro phagocytosis studies and supported by the susceptibility to systemic autoimmunity of carriers of genetic deficiencies for early complement proteins. The present review summarizes the role of molecules of innate immunity in the handling of apoptotic cells by macrophages and dendritic cells. It is proposed that C1q and other opsonins prevent autoimmunity and maintain self-tolerance by supporting the efficient clearance of apoptotic material, as well as by actively modulating phagocyte function.

Animals↗