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PubMed1976

[Splenectomy for traumatic rupture of the spleen in childhood and its sequaelae].

This study was undertaken in order to assess the clinical and immunological consequences of splenectomy for traumatic reasons in childhood. Immunological testing of 22 persons 1 to 20 years subsequent to removal of the spleen for traumatic rupture between the ages of 3 and 6 revealed diminished or absent agglutinins in 10 cases and diminished or absent opsonins to E. coli in 16 cases. All patients were in good health and no clinical evidence of increased susceptibility to severe infections was found postoperatively. It is, therefore, assumed that the diagnosed defects had been compensated for by other immunological mechanisms. In contrast to the opinions of other authors, it is concluded that splenectomy in childhood between the ages of 3 and 6 does not appear to carry greater risks than in later years.

Antibodies, Bacterial↗

PubMed1994

Structure and biological activity of a 1,3-beta-D-glucan-binding protein in crustacean blood.

The prophenoloxidase activating system, an enzyme cascade present in arthropod blood, has been shown to be involved in defense and recognition reactions. This system is converted to its active form by fungal 1,3-beta-D-glucans through binding to a plasma protein, a 1,3-beta-D-glucan-binding protein. Here the molecular cloning and carbohydrate composition of the 1,3-beta-D-glucan-binding protein from the freshwater crayfish Pacifastacus leniusculus are reported. It is also demonstrated that this protein can act as an opsonin, stimulating phagocytic uptake of yeast particles by isolated blood cells. The deduced amino acid sequence of 1,339 residues shows no significant similarity to proteins with similar functions in other animals such as the mannan-binding and lipopolysaccharide-binding proteins present in mammals. However, a short sequence motif with similarity to the active site of microbial 1,3-1,4-beta-D-glucan 4-glucanohydrolases was found to occur twice in the 1,3-beta-D-glucan-binding protein.

Amino Acid Sequence↗

PubMed1994

Anti-lipopolysaccharide antibody levels in patients with AIDS at the onset of Pseudomonas aeruginosa bacteremia.

Lipopolysaccharide (LPS) in the cell wall of the P. aeruginosa is a major factor in the pathogenicity and virulence of this organism. Immunotype-specific serum antibodies to this LPS antigen (ALPS) are usually elevated with the onset of the bacteremia, act as opsonins, are protective in high levels, and are significantly associated with improved survival. In the present study, the ability of 11 patients with AIDS to mount a specific ALPS response with the onset of P. aeruginosa bacteria was evaluated prospectively. Of the 11 patients with AIDS only one had a substantial ALPS response, six mounted only a marginal ALPS response, and four had no ALPS response to the infecting strain of the P. aeruginosa. These data suggest most patients with AIDS do not exhibit a marked antigen-specific humoral response at the onset of P. aeruginosa bacteremia; this has important prognostic and therapeutic significance, as high ALPS titers are associated with survival.

Acquired Immunodeficiency Syndrome↗

PubMed1994

Antibacterial peritoneal defence in automated peritoneal dialysis: advantages of tidal over continuous cyclic peritoneal dialysis?

In tidal peritoneal dialysis (TPD) only a part of the infused dialysate is drained with each exchange, leaving a residual volume on top of which fresh fluid is cycled. As the persistent presence of a buffered intraperitoneal reserve volume might favour peritoneal macrophage (PMO) function, PMO obtained from eight patients during a 3-h continuous cyclic peritoneal dialysis (CCPD) or TPD session were studied in a randomized cross-over trial. PMO were studied for uptake of E. coli (complement-dependent) and S. epidermidis (antibody-dependent), as well as for their killing capacity and peak chemiluminescence response. In addition, dialysate was sampled during both treatment sessions and studied for pH, osmolality, and effect on the viability of donor phagocytes and mesothelial cells. TPD-derived PMO were significantly better able to phagocytose E. coli than CCPD-PMO (48 +/- 8 versus 33 +/- 6% uptake, P < 0.05), whereas the other tested functional capacities revealed no significant difference between TPD- and CCPD-PMO. During TPD dialysate pH ranged from 6 to 7 as compared to a pH range from 5 to 7 in CCPD. The presence of a residual dialysate volume resulted in less wash-out of cells and opsonins early in the treatment, and to some extent blunted the noxious effects of fresh dialysis solutions. Overall, however, tidal PD appeared to have no advantage over CCPD regarding preservation of peritoneal defences.

Adult↗

PubMed1993

Purification of surface-exposed integral outer membrane proteins of Actinobacillus pleuropneumoniae and their role in opsonophagocytosis.

Previously identified 39-, 50-, and 76-kd integral outer membrane proteins (IOMP) of Actinobacillus pleuropneumoniae, a respiratory tract pathogen, were separated by electroelution of sodium dodecyl sulfate-polyacrylamide gel electrophoresis-obtained fragments and their role in opsonophagocytosis by porcine leukocytes was investigated by flow cytometry of fluorescein-labeled A pleuropneumoniae. Using specific antisera, immunoblot analysis indicated that the 3 proteins were antigenically distinct. Antibodies against each IOMP have an important role as opsonins for phagocytosis by porcine leukocytes. The effect of using a combination of all 3 of the specific antisera was minimal. Antiserum absorbed against intact A pleuropneumoniae and Escherichia coli organisms indicated that the antibodies to the 39-, 50-, and 76-kd IOMP were specific for A pleuropneumoniae antigens. Nonheat-treated antiserum did not increase phagocytosis, compared with heat-inactivated antiserum, indicating that complement may not have a major role in opsonization of A pleuropneumoniae.

Actinobacillus pleuropneumoniae↗

PubMed1993

Inhibition of C3 and IgG proteolysis enhances phagocytosis of Porphyromonas gingivalis.

In the face of an apparently competent immune response to Porphyromonas gingivalis, it is unclear how P. gingivalis evades the immune response and persists in human periodontitis. Particularly germane may be its ability to resist phagocytosis by degrading and not binding serum opsonins. In our study, the resistance by invasive (W83 and A7436) and noninvasive (ATCC 33277) P. gingivalis strains to phagocytosis by human neutrophils was compared with their C3- and IgG-proteolytic activity. The ability of opsonic human serum antibody to inhibit C3 proteolysis was also evaluated. Our results indicate that the more phagocytosis-resistant invasive strains accumulate less 125I-C3 than the noninvasive strain; moreover, invasive strains degrade complement C3 in a dose-dependent manner, inhibitable by rabbit antiserum or adult periodontitis serum. Opsonization and C3 accumulation on strain A7436 were both facilitated by pretreatment with rabbit antiserum, certain adult periodontitis sera, protease inhibitors (p-chloromercuriphenylsulfonic acid, N alpha-p-tosyl-L-lysine chloromethyl ketone, diisopropylfluorophosphate), heat (60 degrees C, 15 min), and were Mg2+ dependent. The sera from 13 human subjects with or without periodontitis were assayed for antibody titers to P. gingivalis (ELISA units), opsonic activity (% of PMN engaged in phagocytosis) and enhancement of C3 accumulation. Statistically significant associations were observed between % of PMN engaged in phagocytosis and % C3 accumulation, between % of PMN engaged in phagocytosis and ELISA units and between % C3 accumulation and ELISA units. Degradation of purified rabbit IgG, but not specific antibody-containing rabbit IgG by P. gingivalis A7436 was observed, and was inhibited by diisopropyl fluorophosphate (DFP) or cold (2 degrees C). Our data suggest that C3 and IgG cleavage by P. gingivalis proteases are inhibitable by antibody and are contributory factors in, but are not the sole determinants of, phagocytosis resistance.

Antibodies, Bacterial↗

PubMed1993

The role of the complement system in the neutrophil functions stimulated in vitro by an alkali-insoluble cell wall fraction of Paracoccidioides brasiliensis.

We investigated the capacity of an alkali-insoluble cell wall polysaccharide fraction (F1) of Paracoccidioides brasiliensis to induce rat polymorphonuclear neutrophil (PMN) migratory and chemiluminescence (CL) responses. Normal rat serum pre-incubated with F1 induced a chemotactic neutrophil response which was fully abolished by heat-inactivation. The participation of the alternative complement pathway was more effective than that of the classical pathway since depletion of factor B by heating at 50 degrees C reduced PMN migration, whereas blockade of the classical pathway with EGTA left the migratory response practically unchanged. Opsonized serum F1 induced a significant release of oxygen radicals from PMN as measured by CL. The complement system was also found to be involved in this activity since serum inactivation at 56 degrees C altered the CL response. In addition to complement-derived fragments, other serum opsonins, probably cross-reacting antibodies, were required for optimal interaction between PMN and opsonized particles. These results contribute to the understanding of the role of fungal components and of the complement system in the inflammatory response observed in paracoccidioidomycosis.

Animals↗

PubMed1996

[The dependence of serum opsonic activity on fibronectin and alpha- 1 acid glycoprotein levels in children with burns].

The concentration of acute phase proteins following burn is known to increase in serum rapidly, while that of fibronectin often decreases. Fibronectin (Fn) has been demonstrated to serve as an opsonin involved in the ingestion phase in phagocytic process. On the other hand, some acute phase proteins such as alpha-1 acid glycoprotein (AG) may inhibit phagocytic activity. In our study, the phagocytic activity of normal granulocytes was decreased by those sera in which a high level of AG was accompanied by a fall in the Fn Level. Attempts to detect a possible link between the acute phase response and fibronectin led as to study whether fibronectin and AG may interact antagonistically on the phagocytic activity of neutrophils. For this reason we calculated the Fn/Ag coefficient. We showed that an Fn/Ag coefficient in normal sera equals more than 0.20. The higher the coefficient, the better the opsonic activity of sera. We propose here that an Fn/AG coefficient may be a useful risk factor for infections in burned patients.

Adolescent↗

PubMedDate not supplied

Defective serum opsonization activity in children aged 6-48 months having acute purulent otitis media.

Serum opsonization of yeast (Saccharomyces) was investigated in 51 patients whose ages were between six and 48 months (median 15 months) with acute purulent otitis media and in an age-matched control group (median 13 months). Opsonization was assessed by measuring yeast particle uptake in an assay based on an electronic count of the unphagocytosed particles in serum by polymorphonuclear leukocytes. Despite normal levels of CH50 and serum immunoglobulins, a defective opsonization was determined in 13.7 percent of the patients (7 in 51). The corresponding figure was 2.9 percent in 103 healthy controls (p < 0.001). On the other hand, 218 percent (5 in 23) of the children having a history of recurrent purulent otitis media showed defective opsonization (p < 0.001). Previously, the presence of an opsonization defect has been linked to low levels of mannan binding lectin (MBL), a calcium dependent serum lectin that acts as an opsonin. Therefore, our findings indirectly support the idea that MBL has an important role as host defense, particularly in the earlier period of life when the antibody repertoire is restricted.

Case-Control Studies↗

PubMed1988

Coagulation augments neutrophil C3b receptors via formation of a protein(s) unrelated to fibrinolysis or C5 activation.

The present study investigated the effect of coagulation on neutrophil complement receptors (CRs) 1 and 3, which are specific for the opsonins C3b and C3bi. Incubation of neutrophils in autologous serum, but not in plasma, increased the mean (+/- SD) expression of CR1 (x3.43 +/- 0.93) and CR3 (x3.07 +/- 0.86), in comparison with incubation in buffer. Serum also increased neutrophil superoxide production in response to opsonized zymosan from 0.48 +/- 0.21 to 1.05 +/- 0.25 nmol/10(6) cells/min. Similarly, calcium conversion of platelet-rich plasma (but not platelet-poor plasma) to serum also increased both CR1 and CR3 expression. This finding, as well as the fact that freeze-thawed platelet-rich plasma (but not platelet-poor plasma) increased CR expression, indicated that platelet constituents were the origin of this CR-inducing activity. Other nonplatelet factors formed during coagulation, such as C5a, fibrinogen degradation products, kallikrein, and factor XIIa, were shown not to be responsible for this CR-inducing activity.

Blood Coagulation Factors↗

PubMed1996

Secretion of Osteopontin by macrophages and its accumulation at tissue surfaces during wound healing in mineralized tissues: a potential requirement for macrophage adhesion and phagocytosis.

Osteopontin (OPN), a noncollagenous, extracellular matrix sialoprotein found at relatively high levels in both normal and pathological mineralized tissues, is expressed by tissue-specific cells in bone, calcified cartilage, and teeth. On the other hand, a hallmark of OPN expression in pathologically mineralizing tissue, and in other soft tissues experiencing a more generalized type of necrotic injury, is the production of OPN by macrophages at the lesion site. In the present study, we have localized OPN and other noncollagenous proteins by ultrastructural colloidal-gold immunocytochemistry using a rat model in which mineralized tissue defects are surgically created in mandibular bone and teeth. The healing response was examined by immunocytochemistry and transmission electron microscopy at 10 min, 3 days and 7 days post-surgery using antibodies against OPN, bone sialoprotein, osteocalcin, bone acidic glycoprotein-75, fibronectin, and amelogenin. Whereas most of these proteins were characteristically distributed within their respective extracellular matrices as described previously, OPN was additionally observed to accumulate as a lamina limitans at surgically exposed bone and tooth surfaces, as well as at the surface of particulate, mineralized tissue debris. Intracellular labeling of the Golgi apparatus and secretory granules of macrophages at the lesion site demonstrated that OPN production by macrophages was a prominent secretory event of the inflammatory response during wound healing in mineralized tissues. Pseudopodal and lamellipodal cytoplasmic extensions of macrophages were observed in direct contact with the OPN-containing lamina limitans at these surfaces. Particulate, calcified debris internalized by macrophages also displayed a prominent surface "coating" of OPN. In conclusion, our interpretation of the present data is that OPN secreted by macrophages may serve as a macrophage adhesion protein, and where concentrated at the surface of small particulate, mineralized tissue debris, may act as an opsonin, thereby facilitating cell adhesion and phagocytosis by macrophages, a process likely mediated by integrin-binding, signal transduction, and cytoskeletal restructuring.

Amelogenin↗

PubMed1999

MPEO-PLA nanoparticles: effect of MPEO content on some of their surface properties.

Nanoparticles of poly(lactic acid) (PLA) and of blends of PLA and monomethoxypoly(ethylene oxyde) (MPEO-PLA) were prepared by the double emulsion method. Sucrose was added to overcome nanoparticle aggregation with freeze-drying. Whereas PLA nanoparticles rapidly are phagocytosed by the mononuclear phagocyte system cells, the uptake of MPEO-PLA nanoparticles is delayed. Opsonization is one of the steps of phagocytosis, and serum complement is a major component of the opsonin system. The in vitro complement consumption of the prepared nanoparticles was evaluated as a function of time and of their surface area. To avoid the aggregation of MPEO-PLA nanoparticles due to MPEO crystallization, sucrose was necessary, and its concentration was dependent on MPEO proportion in the nanoparticle suspension. As expected, the complement consumption for PLA nanoparticles is faster and more important than for PLA/MPEO-PLA blends. The complement consumption decreases with the increase in MPEO surface density. Complement is less consumed with the lower surface density provided by a higher molecular weight than by the higher surface density provided by a lower molecular weight MPEO. The complement consumption seems to be dependent on the number of nanoparticles in contact with human serum. Finally, the model of steric repulsion of MPEO towards proteins and the importance of the surface density of MPEO were emphasized.

Biocompatible Materials↗

PubMed1996

Size-dependent release of carboxyfluorescein from cetylmannoside-modified liposomes in human plasma.

The interaction of liposomes with human plasma was investigated using 6(5)-carboxyfluorescein (CF) as an aqueous phase marker of cetylmannoside-modified multilamellar vesicles (Man-MLVs) of various sizes. The release of CF decreased with increasing liposome concentration. The time courses of the CF release from Man-MLVs were monitored continuously and were analysed kinetically. The curves were characterized by two phases, the first-order release process and the maximum release, which represent the rate and the extent of CF release, respectively. The increase of liposome size increased the rate of release by 42% and the extent of release by 121%, respectively. These effects of liposome size on the release processes were suggested to result from the size-dependent affinities of liposomes to the human complement system. The assay system of liposomally bound fragments of complement component 3 (C3), such as C3b and/or iC3b, was developed by applying a sandwich enzyme-linked immunospecific assay. The percentage of C3 fragments to total proteins bound to liposomes increased with the size of liposomes and there was a good correlation between the extent of CF release and the percentage of C3 fragments bound. These results indicated that Man-MLVs released entrapped CF via activating the human complement system and the affinity of Man-MLV to complement increased with the size of Man-MLVs in human plasma. These in vitro results suggest the role of complement as an opsonin in the disposition of Man-MLVs in humans.

Drug Carriers↗

PubMed1977

Overwhelming postsplenectomy infection.

One of the more intriguing aspects of the spleen is the protection against certain bacterial infections afforded by its unique vascular and immune function. There have been extensive clinical surveys which indicate an incidence of overwhelming postsplenectomy infection (OPSI) above that of the disease for which the splenectomy was done. In the absence of the spleen, either congenital or subsequent to surgical removal, this overwhelming sepsis has a 50% case fatality rate. The most common infective organism has been Diplococcus (tstreptococcus) pneumoniae (D. pneumoniae). Intensive investigations indicated loss of phagocytic function of the spleen, depression of serum IgM levels, a possible suppression of the lymphocyte responsiveness, and changes in opsonin-alternative complement system as potential causes of OPSI. Preventive measures against OPSI include trials of prophylactic Phenoxymethyl Penicillin (penicillin) and pneumococcal vaccine.

Adolescent↗

PubMed1985

Defective complement activity in chronic lymphocytic leukemia.

Patients with chronic lymphocytic leukemia (CLL) are at an increased risk for infections with bacteria which require complement for osponization. We explored the possibility that patients with CLL have a defect in binding the potent opsonin C3b to bacteria. Bacteria selected for these experiments included Streptococcus pneumoniae type 3, which binds C3 by activating the classical complement pathway (CCP), type 25, which can bind normal amounts of C3b by the alternative complement pathway (ACP), type 14, which can activate both the CCP and ACP, and Staphylococcus aureus and Escherichia coli, both of which activate the CCP. Bacteria were treated with normal serum or serum from 15 patients with CLL, and the bound C3b was quantified spectrophotofluorometrically. Despite normal serum concentrations of C3, C4, Factor B, C-reactive protein, and total hemolytic complement activity, all 15 CLL sera bound reduced amounts of C3b to at least one bacterial species; 9 to S pneumoniae type 3, 8 to types 14 and 25, 11 to S aureus, and 13 to E coli. Mixing normal serum with CLL serum restored C3b binding to all bacteria, suggesting a deficiency rather than an inhibitor of activity. Serum from ten hypogammaglobulinemic CLL patients bound less C3b (62.7 +/- 5% of normal) (means +/- SEM) than those with normal immunoglobulin levels (81.9 +/- 5%) (p less than .005). Nevertheless, the addition of specific antibacterial antibodies to CLL serum did not enhance C3b binding to any of the bacteria. Serum from patients with a history of a bacterial infection bound less C3b (62.3 +/- 5%) than those without a history of infections (76.1 +/- 6%) (p less than .05). Thus, there is a defect in either the activation or activity of C3 in CLL serum which may contribute to the increased incidence of infections in these patients.

Blood Bactericidal Activity↗

PubMed2001

Immunopathology of secondary-progressive multiple sclerosis.

Twenty-three plaques obtained at early autopsy from 2 patients with secondary-progressive multiple sclerosis were examined immunohistochemically for microglia/macrophages, and for immunoglobulins and components of activated complement. Most of the lesions examined in both cases exhibited evidence of low-grade active demyelination of an unusual type (frustrated phagocytosis) in periplaque white matter. This included linear groups of microglia engaging short segments of disrupted myelin that were associated with deposits of C3d, an opsonin formed during complement activation. Similar microglia/C3d/myelin profiles were not observed in newly forming lesions in cases of acute multiple sclerosis or other central white matter diseases. As C3d coupling is known to increase the immunogenicity of potential antigens enormously, present findings point to disrupted myelin close to plaques as a possible source of the putative multiple sclerosis antigen. Ongoing myelin destruction found in a high proportion of old, established plaques was surprising. It suggests that slowly expanding lesions (progressive plaques), in which ongoing myelin breakdown occurs in the absence of florid perivascular cell cuffing or other histological signs of acute inflammation, contribute to disease progression in cases of secondary-progressive multiple sclerosis.

Adult↗

PubMed1985

The immunoreactivity, ligand, and cell binding characteristics of rheumatoid synovial fluid fibronectin.

Fibronectin promotes macrophage adherence and expression of Fc receptors, is chemotactic for fibroblasts, and is an opsonin for fibrin and denatured collagen. These properties suggest a role for fibronectin in the modulation of joint inflammation. Since structural modification of the fibronectin molecule has been shown to result in loss or de novo acquisition of opsonic and chemotactic activity, we determined the functional and immunochemical properties of fibronectin isolated from the inflamed joint. Eighty-six percent of synovial fluids obtained from patients with active rheumatoid arthritis (RA) contained fibronectin fragments, and 39% of the fluids no longer displayed the dimeric form. Compared with native fibronectin, RA peptides were as active in promoting synoviocyte chemotaxis and in glycosaminoglycan binding, but displayed lower affinity for fibrin and gelatin. Although comparable with intact protein in augmenting monocyte attachment to gelatin, the RA synovial fluid peptides did not augment monocyte attachment to fibrin. Analysis of whole synovial fluid and isolated fibronectins by enzyme immunoassay showed that the increased fibronectin immunoreactivity, previously reported in RA synovial fluid, measures intact and nearly intact protein and does not measure extensively degraded fragments.

Animals↗

PubMed1984

Plasma fibronectin and complement in surgical patients.

Plasma fibronectin and a fragment of the third component of complement (C3b) are both opsonins of the reticulo-endothelial system. Twenty patients undergoing uncomplicated gastro-intestinal surgery were studied. There was a significant reduction in plasma fibronectin and total haemolytic complement, but not C3, in the early postoperative period (days 1 to 3). In six surgical patients critically ill with severe sepsis both plasma fibronectin concentrations and C3 concentration were reduced significantly when compared with the early postoperative period of uncomplicated surgery. In addition, in the critically ill patients, direct evidence of complement activation was demonstrated. These studies show a transient reduction of humoral host defence mechanisms following surgery which may be permissive to bacteraemia and complement activation.

Adult↗