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PubMed1981

Assessment of Haemophilus influenzae type b opsonins by neutrophil chemiluminescence.

A luminol-enhancement chemiluminescence assay and a radiolabeled uptake assay were developed to assess opsonins for Haemophilus influenzae type b. Opsonins in acute and convalescent sera from 17 children with H. influenzae type b meningitis, along with pooled normal human sera, were evaluated and compared with anti-polyribosephosphate antibody concentrations. Five children had a rise in the chemiluminescence-area under the curve for convalescent compared with acute sera. Patient chemiluminescence--area-under-the-curve values were significantly (P less than 0.05) more likely to exceed 50% of normal human serum values if sera contained greater than or equal to 0.1 microgram of anti-polyribosephosphate antibody per ml. Magnesium ethylene glycol tetraacetic acid chelation and heat inactivation of patient and normal human sera significantly (P less than 0.05) reduced chemiluminescence--area-under-the-curve activity. Thus, complement appears to contribute significantly to the opsonization of H. influenzae type b in sera of children. Two of nine children had increases in opsonins as assayed by 3H-labeled H. influenzae type b uptake. After natural systemic H. influenzae type b infection, young children are unable to respond acutely with an increase in anti-polyribosephosphate antibody or serum opsonic activity.

Antibodies, Bacterial↗
PubMed1995

Concentrations of main serum opsonins in early infancy.

The evolution of the main serum opsonins in neonates and infants of varying gestational age was investigated to provide reference values for these opsonins in early infancy. Serum concentrations of immunoglobulins, IgG subclasses, C3, C4 and fibronectin were serially measured from birth until the age of 6 months in term and preterm infants. Measurements were performed by rate nephelometry. Five hundred and sixty six neonates (gestational age 26-41 weeks) were examined at birth, 233 at 1 month, 218 at 3 months, and 147 at 6 months, respectively. The same measurements were performed in 54 pairs of neonatal/maternal samples and in 230 apparently healthy adults. Gestational age had a significant impact on serum IgG, IgG subclasses, C3 and C4 up till the third month, and on fibronectin until the first month. No such impact was observed for IgA and IgM. Sixteen per cent of the neonates had IgM concentrations higher than 0.2 g/l at birth, suggesting that the critical concentration of serum IgM at birth for suspected intrauterine infection should be reconsidered. Concentrations of all opsonins at birth were significantly lower than adult reference values. They only approached or even reached adult values by the third or the sixth month. Data from analysis of the neonatal and the corresponding maternal sera indicate that there is a preferential active transplacental transport of IgG subclasses in the order of IgG1, IgG3, IgG2 and IgG4. These results show that concentrations of immunoglobulins, C3, C4 and fibronectin undergo changes during the first months of life, depending not only on the infants' postnatal age but also on gestational age.

Complement C3↗
PubMed2001

Interactions of liposomes with cells in vitro and in vivo: opsonins and receptors.

A number of studies have appeared recently on the underlying mechanisms of liposome-cell interactions under in vitro conditions, in which isolated cell populations or cell lines were used. However, our knowledge of how liposomes interact with cells and the parameters that influence this in vivo is limited. We will summarize and discuss the relevant studies on this matter in this article. In addition, researchers in this field have long been aware of the interaction of liposomes with blood (or serum/plasma) proteins in vivo and their potential role in the process of the clearance of liposomes from the circulation. Some of the 'opsonizing' proteins, such as complement components, immunoglobulins, which enhance the interactions of liposomes with 'phagocytic cells' have been identified. However, the issue of which types of opsonins determine the fate of liposomes in vivo and how liposomal physicochemical properties such as size, charge and fluidity play an important role in the process of liposome clearance is not clear. Our own observations of one of opsonins, complement component are reviewed herein. As opposed to the fate of conventional liposomes, we briefly touch on the interaction of surface-modified liposomes, which are designed to avoid interactions with blood proteins and/or cells (sterically stabilized liposomes, long-circulating liposomes) and to actively target specific cells or tissues (targeted liposomes: immunoliposomes). Blood proteins such as opsonins are not usually thought to play an important role in the clearance of such liposomes.

Antineoplastic Agents↗
PubMed1975

Heat labile opsonin system to pneumococcus.

Normal mammalian sera contain the heat labile opsonin system that promotes the phagocytosis of various microorganisms by polymorphonuclear leukocytes. Because the heat labile opsonin system is present in normal nonimmune sera and because it operates against various microorganisms in an apparently nonspecif manner, it is considered to play an important role during the early phase of an acute bacterial infection. The role of various factors participating in the heat labile opsonin system, and its in vivo significance are discussed.

Animals↗
PubMed1986

The influence of opsonins on the bactericidal effect of bovine alveolar macrophages against Pasteurella multocida.

Monolayers of bovine alveolar macrophages were infected with smooth and rough strains of Pasteurella multocida to determine their bactericidal function. Heat inactivated normal bovine serum, fresh bovine serum, specific immune serum and a combination of specific immune serum and fresh bovine serum were used as opsonins. A substantial difference in the bactericidal effect of macrophages against the logarithmic and stationary phase p. multocida was observed. Opsonization of the rough strain of P. multocida with the combination of specific immune and fresh serum increased their association with alveolar macrophages compared to those opsonized with either normal serum, fresh serum or specific immune serum. Opsonization of the smooth strain of P. multocida with normal bovine serum resulted in substantially fewer bacteria associated with macrophages at time zero, compared with other opsonins. Regardless of the kind of opsonins used in these experiments, the number of the rough strain of P. multocida killed by macrophages was always higher than those of the smooth strain.

Animals↗
PubMed2001

Opsonin receptor expression on peritoneal exudative and circulatory neutrophils in murine acute pancreatitis.

Acute severe (necrotizing) pancreatitis is often associated with pancreatic or peripancreatic infection. Decreased bacterial clearance due to impaired immune defense may cause local infection. We investigated expressions of surface opsonin receptors (CD11b, complement receptor 3; CD32/CD16, immunoglobulin G Fc receptor) on local and circulatory neutrophils, in murine acute pancreatitis. The mild and severe forms of acute pancreatitis were induced by seven and 13 subcutaneous injections of caerulein, respectively. Peritoneal exudative and circulatory neutrophils were counted and assayed for receptor expressions by flow cytometry, serially at 1-72 hours after pancreatitis induction. Histologically, mild and severe forms showed edematous and necrotizing pancreatitis, respectively. The peritoneal exudative neutrophil count was greater in mild than in severe pancreatitis. Expressions of CD11b and CD32/CD16 on local neutrophils were upregulated early in mild pancreatitis. This upregulation was attenuated in severe pancreatitis. The circulatory neutrophil count was elevated in severe pancreatitis but was unchanged in mild pancreatitis. Opsonin receptor expression on circulatory neutrophils showed a transient, modest upregulation in the early phase of mild pancreatitis. Receptor-positive circulatory neutrophils showed a marked elevation that persisted throughout the course of severe pancreatitis. In conclusion, severe (necrotizing) pancreatitis is associated with reduced opsonin receptor expression on local neutrophils and enhanced expression on circulatory neutrophils, as compared with mild (edematous) pancreatitis. These changes may contribute to local infectious complications and multiple organ failure, in severe pancreatitis.

Acute Disease↗
PubMed2005

Effect of granulocyte colony-stimulating factor on opsonin receptor expression in cerulein-induced acute pancreatitis.

OBJECTIVES: Decreased levels of expression of opsonin receptors (CD11b and CD32/16) on peritoneal exudate neutrophils may lead to susceptibility to infection. Granulocyte colony-stimulating factor (G-CSF) increases the expression levels of CD11b on neutrophils and prolongs neutrophil survival. The effects of G-CSF on neutrophils and opsonin receptor expressions of neutrophils were investigated in cerulein-induced acute pancreatitis. METHODS: Forty-two mice were randomly assigned to each group (n = 6). Mice received subcutaneous G-CSF (120 microg/kg body weight) before the induction of acute pancreatitis with cerulein. Saline was used for instead of G-CSF or cerulein solution in control groups. CD11b and CD32/16 expression levels on circulatory and peritoneal exudate neutrophils were investigated 6 and 24 hours after the induction of acute pancreatitis. RESULTS: Treatment with G-CSF did not aggravate the inflammation of pancreatic tissue evaluated by plasma amylase, acinar necrosis. However, it significantly increased the number of peritoneal exudate neutrophils (P < 0.05) and the CD11b- (P < 0.05) and CD32/16-positive (P < 0.05) peritoneal exudate neutrophils in mice with cerulein-induced acute pancreatitis. The means of fluorescence intensity for CD11b and CD32/16 expressions on circulatory and peritoneal exudate neutrophils were also elevated in the G-CSF groups. CONCLUSION: G-CSF administration increases the numbers of neutrophils and improves expression levels of opsonin receptors on neutrophils in mice with cerulein-induced acute pancreatitis.

Acute Disease↗
PubMed1997

Surfactant protein A, but not surfactant protein D, is an opsonin for influenza A virus phagocytosis by rat alveolar macrophages.

Surfactant protein A (SP-A) and surfactant protein D (SP-D) are collectins, and both proteins were shown to interact with influenza A virus and alveolar macrophages. However, it is not known whether SP-A and SP-D can serve as opsonins for the phagocytosis of influenza A virus by alveolar macrophages. In the present study, we investigated the opsonic activities of SP-A and SP-D for phagocytosis of fluorescein isothiocyanate (FITC)-labeled influenza A (H3N2) virus by rat alveolar macrophages using flow cytometry. SP-A enhanced the association of the virus with macrophages in a dose-dependent manner, reaching a maximum at an SP-A concentration of 60 microg/ml. An approximate threefold increase in association of influenza A virus with alveolar macrophages in the presence of SP-A over control incubations which contained no SP-A was observed. Half of the total cell-associated fluorescence could be quenched as demonstrated using the extracellular quenching dye trypan blue. These results indicate that SP-A mediates internalization of FITC-labeled influenza A (H3N2) virus by alveolar macrophages. Removal of the carbohydrate moiety of SP-A by N-glycosidase F treatment or cleavage of its sialic acid residues by neuraminidase abolished the enhancement of the phagocytosis of FITC-labeled influenza A virus by alveolar macrophages. Mannan, a mannose homopolysaccharide known to bind to the carbohydrate-binding domain of SP-A, did not affect the SP-A-mediated phagocytosis of FITC-labeled influenza by alveolar macrophages. In contrast, SP-D neither enhanced the association of FITC-labeled influenza A virus with alveolar macrophages nor affected the opsonic activity of SP-A for FITC-labeled influenza A (H3N2) virus at the SP-D concentrations tested. It is concluded that SP-A acts via its sialic acid residues as an opsonin in the phagocytosis of influenza A virus by alveolar macrophages.

Animals↗
PubMed1988

Tissue specific opsonins for phagocytic cells and their different affinity for cholesterol-rich liposomes.

In accordance with the finding of our in vivo experiments reported earlier [(1983) Biochim. Biophys. Acta 761, 142-157; (1986) Biochim. Biophys. Acta 888, 184-190], the results of in vitro experiments show that Kupffer cells avidly take up cholesterol-poor but not cholesterol-rich liposomes, whereas splenic phagocytic cells take up preferentially cholesterol-rich rather than cholesterol-poor liposomes in the presence of serum. Evidence presented here suggests that serum contains opsonins specific for hepatic and splenic phagocytic cells and these opsonins have different affinities for cholesterol-rich and cholesterol-poor liposomes.

Adsorption↗
PubMed1985

Quantitative evaluation of opsonin-independent phagocytosis by alveolar macrophages in monolayer using polystyrene microspheres.

Macrophages can bind and engulf a variety of particles in the absence of specific opsonins. Polystyrene-type microspheres are often employed to quantitate opsonin-independent phagocytic activities of macrophages in vitro. Reliable measurement of this cell function, however, requires the ability of the investigator to distinguish between particles that are merely attached to the cell surface and those that are actually internalized. We have developed a simple, rapid, and reproducible method for quantitating phagocytosis using polystyrene microspheres and adherent alveolar macrophages. Basically, particles associated with macrophages after a given incubation time are microscopically quantitated on a cell-by-cell basis before and after toluene dissolution of external particles. Particle/macrophage values obtained after toluene treatment exclusively index phagocytosis.

Animals↗
PubMed1989

Flow cytometric assay for the measurement of serum opsonins to Neisseria meningitidis serogroup B, serotype 15.

A flow cytometric phagocytosis assay has been developed for the measurement of human serum opsonins to serogroup B meningococci. Live bacteria and bacteria inactivated by heat, formalin or ethanol were labelled with fluorescein-isothiocyanate (FITC). The bacteria were opsonized with sera from patients with group B meningococcal disease and sera from healthy controls, and phagocytosis determined by combined measurements of FITC-fluorescence and forward angle light scatter. Optimal sensitivity was obtained using viable bacteria, 5% serum, 20 bacteria per leukocyte capable of phagocytosis, 7.5 min opsonization time, 5 min phagocytosis time, 37 degrees C, and continuous agitation during opsonization and phagocytosis. The opsonic activity of sera from convalescent patients was markedly higher than that of sera from patients with acute illness. Only minor day-to-day and interindividual variations were observed. The flow cytometric phagocytosis technique is a rapid and reproducible method for the measurement of serum opsonins to meningococci.

Blood Bactericidal Activity↗
PubMedDate not supplied

Humoral opsonins of the tunicate, Pyura stolonifera.

This study characterizes humoral opsonins from the tunicate, Pyura stolonifera. The predominant opsonic components in P. stolonifera hemolymph were found to be calcium-dependent lectins with broad carbohydrate specificities. The opsonic lectins were purified by carbohydrate affinity chromatography which eluted a complex pattern of proteins ranging in molecular mass from 80 to >200kDa. Reducing and two dimensional SDS-PAGE indicated that the diversity of mature lectins evident under non-reducing conditions resulted from the differential oligomerization of two polypeptide sub-units (35 and 22kDa). In addition to lectin-mediated opsonic activity, hemolymph was also found to contain proteolytically activated opsonins. These data suggest that multiple, possibly interactive opsonic systems co-exist in P. stolonifera.

Animals↗
PubMedDate not supplied

Serum opsonins and chemotactins in neutropenic oncology patients.

Serum opsonins and chemotactins, C3 and C5, were studied in neutropenic oncology patients. Our data indicate that these individuals possess normal serum chemotactins and adequate opsonin activity regardless of disease status or prior chemotherapy. Their sera should therefore support function of transfused granulocytes.

Adolescent↗
PubMed1969

Heat labile opsonins to pneumococcus. I. Participation of complement.

Heat labile opsonins (HLO) in normal rat serum to both encapsulated and unencapsulated pneumococci (a) have the same heat lability as complement (C); (b) are active at 37 degrees C but not at 0 degrees C; (c) are inactivated proportionately to hemolytic C by the addition of immune aggregates to the serum; (d) are adsorbed from serum nonspecifically by bacteria at 37 degrees C but not at 0 degrees C; (e) are Ca(++)- and/or Mg(++)-dependent in their action; and (f) are inactivated by zymosan and a purified cobra venom factor, and in the case of encapsulated pneumococci, at least, by NH(4)OH. Like other opsonins, HLO to pneumococci act primarily on the bacteria rather than on the phagocytes. Their combined properties indicate that they involve multiple components of the hemolytic C system. Since HLO are immunologically polyspecific, they presumably play a broad protective role in the early (preantibody) phase of acute bacterial infections.

Adsorption↗
PubMed1970

The relationship between group A and group C meningococcal polysaccharides and serum opsonins in man.

The interaction in vitro between human granulocytes and meningococci in the presence of sera from volunteers immunized by Gotschlich et al. with purified group A and group C meningococcal polysaccharides was studied. Phagocytosis of meningococci did not occur in the presence of preimmunization sera. In all volunteers tested, group-specific opsonins were detected in groups A and C polysaccharide antisera. Opsonic activity appeared within 1 wk after immunization and persisted for at least 14 months. Titers of opsonic activity ranged from 1:20 to 1:320; highest titers were noted in 2-4 wk antisera. Meningococcal opsonins were detected in both 19S and 7S immunoglobulins. Opsonic activity in low-titer antisera depended on heat-labile factors present in both normal and immune sera, whereas phagocytosis was observed in the presence of heat-inactivated high-titer antisera. Phagocytosis of group A meningococci in the presence of certain group A polysaccharide antisera was inhibited by N-acetyl mannosamine, but not by mannose, mannosamine, N-acetyl glucosamine, N-acetyl galactosamine, or N-acetyl neuraminic acid. Absorption studies with sera from patients with natural meningococcal infections revealed that these polysaccharides are the major antiphagocytic determinants for group A and group C meningococci. These studies are consistent with previous reports suggesting that immunization with group A and group C polysaccharides may well provide group-specific protection against meningococcal infections.

Antibodies↗
PubMed2002

Opsonin-independent phagocytosis: an effector mechanism against acute blood-stage Plasmodium chabaudi AS infection.

Opsonin-independent macrophage phagocytosis was investigated as a possible mechanism of controlling early blood-stage Plasmodium chabaudi AS infection. Early during infection, peritoneal macrophages from resistant C57BL/6 (B6) mice exhibited increased phagocytosis of parasitized red blood cells (pRBCs) and free merozoites, which was absent in mice with deficient interferon (IFN)-gamma production during infection, including susceptible A/J, interleukin (IL)-12 p40, and IFN-gamma gene knockout mice. IFN-gamma treatment of macrophages collected from B6 and A/J mice early during infection enhanced phagocytosis of pRBCs, but IL-10 treatment inhibited this function. In vitro and in vivo studies in which type I and II class A scavenger receptor-deficient mice and inhibitors of scavenger and mannose receptors were used revealed that scavenger receptors other than class A type I and II and mannose receptors may play a role in malaria parasite uptake. These results indicate that opsonin-independent phagocytosis contributes to the IFN-gamma-dependent control of acute blood-stage malaria infection.

Acute Disease↗
PubMedDate not supplied

Complement and opsonins in alveolar secretions and serum of rats with pneumonia due to Streptococcus pneumoniae.

Complement appears to have an important role in the early defense against Streptococcus pneumoniae, but the role of complement as a defense mechanism within the lung is not well defined. Complement and heat-labile opsonins in pneumococcal pneumonia were studied by analysis of bronchoalveolar lavage fluid (BALF) of rats inoculated intratracheally with type 3 S. pneumoniae. BALF and serum were obtained at 0, 6, and 24 hr after infection. Leukocyte counts in BALF and histologic studies revealed an acute inflammatory response in the lung at 6 hr; this inflammation progressed for 24 hr. Levels of C1, C2, C3, and alternative pathway activity in pooled, concentrated (20X) BALF of normal and infected rats varied according to the stage of infection and the complement parameter studied, but in all cases the levels were only a small fraction of the levels in serum. Concentrated BALF had measurable levels of pneumococcal heat-labile opsonins, but these were also low as compared with serum levels. A small amount of C3 was detected by immunofluorescence on pneumococci recovered from BALF of infected animals, but these same organisms could be coated much more fully with C3 by brief incubation in serum. The milieu in the lung during bacterial infection is very different from that in serum and may be marginally suitable for effective opsonization of successful pulmonary pathogens such as type 3 S. pneumoniae.

Animals↗
PubMed1980

Complement, opsonins, and the immune response to bacterial infection in burned patients.

Studies were performed to evaluate complement, opsonins, and the immune response to bacterial infection in burned patients. Concentrations and functional acitivities of components of the classical and alternative complement pathways were measured in the sera of four septic, two bacteremic, and four nonseptic burned patients. In addition, heat-labile and heat-stable opsonic activity and agglutinin titers directed against the infecting bacterial strains were measured in the sera of the four septic patients and in an additional group of 11 septic burned patients with abnormal complement profiles. Functional activity of the alternative complement pathway and the concentration of properdin were shown to be persistently decreased during eight weeks postburn in the septic, bacteremic, and nonseptic burned patients; reduced classical pathway activity was demonstrated during the initial postburn period only in the septic patients. Two of the 15 septic patients had decreased heat-labile serum opsonic activity for their infecting bacterial strains, which occurred only during the initial postburn period. Heat-stable opsonins and agglutinin titers in the patients' sera directed against the infecting bacterial strains were equivalent to those in normal human sera, except for the agglutinin titers to Streptococcus faecalis which were increased in the patients' sera in comparison to the normal sera. These results indicate that the multiple complement abnormalities which occur in septic burned patients do not predispose these patients to bacterial infection by decreasing serum opsonic activity. Moreover, heat-stable immune IgG antibodies are not produced during septicemia which facilitate opsonization of the infecting bacterial strains in the absence of an intact complement system.

Adolescent↗