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At least 343 records · Page 19Linked to original sources
PubMed1984

Proteins of the cystic fibrosis respiratory tract. Fragmented immunoglobulin G opsonic antibody causing defective opsonophagocytosis.

In the disease cystic fibrosis (CF), pulmonary infection with Pseudomonas aeruginosa is a common clinical complication that determines most morbidity and almost all excess mortality. We postulated that in this disease a defect in Pseudomonas-reactive IgG antibodies may contribute to chronic Pseudomonas infections. Bronchoalveolar lavages were performed upon 13 patients with CF, 7 patients with chronic bronchitis characterized by recurrent Pseudomonas infections, and 4 normal volunteers. The levels of various proteins important to host defenses and proteases were determined; enzyme inhibition studies were performed. CF respiratory immunoglobulin levels were significantly elevated when compared with both normals and patients with chronic bronchitis (P less than 0.05). Albumin and transferrin levels were decreased in the CF lung fluids. CF elastolytic activity was strikingly elevated (means = 6.02 micrograms/mg total protein) and the inhibitory profile suggested such activity resembled a serine-proteinase. Alpha-1-antitrypsin antigenic levels were not altered in CF respiratory fluids. There was a tendency for the lavage IgG to fall as elastase levels rose (r = -0.29). IgG opsonins for two Pseudomonas immunotypes were isolated with affinity chromatography for functional and immunochemical studies. Bacterial phagocytic rates in the presence of these Pseudomonas-reactive IgG opsonins derived from CF lavage fluid were depressed (0.3% uptake/unit time) when compared with similarly titered positive controls (uptake = 1.3%/unit time, P less than 0.001). Additionally, normal pulmonary macrophage intracellular killing of Pseudomonas was severely altered in the presence of opsonins derived from CF respiratory fluids. At some time points, less than 30% of the bacteria were killed. CF IgG opsonins contain a cleavage fragment (100,000 D, 5S sedimentation coefficient) with antigenic determinants similar to the Fab portion of IgG. The presence of such a fragment was inversely correlated with phagocytic functional activity. Intact IgG comprised as little as 18% of the CF lavage fluid specimens. Aliquots of intact human IgG, when mixed with the CF opsonins, augmented Pseudomonas uptake and improved intracellular killing. Conversely, peptide fragments of IgG opsonins, which are proteolytically derived in vitro, duplicated in our system the defect observed with opsonins derived from CF lung fluids; bacterial uptake was inversely related to the concentration of F(ab')2 and to a greater degree, to Fc present in the opsonic mixture. We concluded that IgG respiratory opsonins are fragmented, inhibiting phagocytosis and serving a permissive role in the chronic Pseudomonas pulmonary infection in the disease CF.

Adult↗
PubMed1984

Kinetic analysis of microbe opsonification based on stimulated polymorphonuclear leukocyte oxygenation activity.

With Pseudomonas aeruginosa as the target microbes and polymorphonuclear leukocytes (PMNL) as effector phagocytes, the microbe-specific, immunoglobulin G (IgG)-dependent opsonic capacities of preimmune and immune sera were measured as the rate of stimulated PMNL dioxygenation of luminol yielding chemiluminescence (CL). When the reactants other than opsonin are present in concentrations that are not rate limiting, the information-effector relationship linking specific opsonin concentration to effector PMNL stimulation is described by the rate equation: L' = k'[IgG]i, where L' is the peak CL velocity (photons per minute), k' is the proportionality constant, [IgG] is the concentration of specific opsonin, and the exponent i is the order of the reaction with respect to opsonin. Since the specific opsonins were polyclonal IgG of unknown absolute serum concentration, the reciprocal rate expression, L' = k'D-i, was employed for data presentation; D is the serum dilution (final volume/initial serum volume), and the sign of i is changed to negative. The relationships of integral, first-derivative, and second-derivative expressions of the CL response to opsonin concentration are illustrated with experimentally obtained data. Based on peak CL velocity or peak CL acceleration measurements taken over different time intervals of testing, the estimated order with respect to opsonin is highest, and probably most accurate, using the shortest test interval allowing reasonably good precision of measurement. As an alternative temporal approach, microbe opsonification kinetics are analyzed based on nodal time (Tn) measurements. The Tn is the time point separating the acceleration and deceleration phases of the PMNL oxygenation response to stimulation and as such satisfies the criterion of a selected condition of PMNL activation.

Kinetics↗
PubMed2000

Protection from lethal gram-positive infection by macrophage scavenger receptor-dependent phagocytosis.

Infections with gram-positive bacteria are a major cause of morbidity and mortality in humans. Opsonin-dependent phagocytosis plays a major role in protection against and recovery from gram-positive infections. Inborn and acquired defects in opsonin generation and/or recognition by phagocytes are associated with an increased susceptibility to bacterial infections. In contrast, the physiological significance of opsonin-independent phagocytosis is unknown. Type I and II class A scavenger receptors (SR-AI/II) recognize a variety of polyanions including bacterial cell wall products such as lipopolysaccharide (LPS) and lipoteichoic acid (LTA), suggesting a role for SR-AI/II in innate immunity to bacterial infections. Here, we show that SR-AI/II-deficient mice (MSR-A(-/-)) are more susceptible to intraperitoneal infection with a prototypic gram-positive pathogen, Staphylococcus aureus, than MSR-A(+/+) control mice. MSR-A(-/-) mice display an impaired ability to clear bacteria from the site of infection despite normal killing of S. aureus by neutrophils and die as a result of disseminated infection. Opsonin-independent phagocytosis of gram-positive bacteria by MSR-A(-/-) macrophages is significantly decreased although their phagocytic machinery is intact. Peritoneal macrophages from control mice phagocytose a variety of gram-positive bacteria in an SR-AI/II-dependent manner. Our findings demonstrate that SR-AI/II mediate opsonin-independent phagocytosis of gram-positive bacteria, and provide the first evidence that opsonin-independent phagocytosis plays a critical role in host defense against bacterial infections in vivo.

Animals↗
PubMed1971

Contribution of humoral and cellular factors to the resistance to experimental infection by Pseudomonas aeruginosa in mice. I. Interaction between immunoglobulins, heat-labile serum factors, and phagocytic cells in the killing of bacteria.

Techniques have been described for the purification of mouse polymorphonuclear leukocytes (PMN) and macrophages and for determining their bactericidal activity against Pseudomonas aeruginosa in a rotating suspension. Requirements for human anti-Pseudomonas opsonins and heat-labile mouse serum factors have been determined. In the macrophage system, although heat-labile mouse serum factors had enhancing properties, both immunoglobulin G (IgG) and immunoglobulin M (IgM) opsonins alone sufficed to induce bactericidal activity. In contrast, both opsonins and heat-labile mouse serum factors were required for bactericidal activity by the mouse PMN. In the absence of heat-labile mouse serum factors, IgG and IgM opsonins contributed to the bactericidal activity of mouse macrophages to the same extent. However, in the presence of these factors, much less IgG than IgM antibody was required to achieve maximum bactericidal activity by these cells. Similarly, IgG opsonins were found to be more efficient than IgM opsonins in enhancing the killing of P. aeruginosa by mouse PMN.

Animals↗
PubMed1986

[Chemiluminescence of whole blood--analysis of the kinetics and application of clinical examination of phagocytic functions of whole blood from various type of diseases].

Luminol-dependent chemiluminescence of whole blood (whole blood CL) was developed to estimate the phagocytic function of granulocytes and the serum opsonin activity simultaneously. Whole blood (0.1 ml) was examined directly and results were obtained within 20 minutes. Phagocytic function of granulocytes can be estimated from the peak CL of whole blood and the number of granulocytes in a specimen, and the opsonin activity from the amount of time the peak CL is shown after the addition of nonopsonized CL inducer (nonopsonized zymosan). Subsequently, whole blood CL was measured to evaluate phagocytic functions in children with disease. Patients with chronic granulomatous disease showed no CL, and one of their mothers (1/3) showed low CL, suggesting she is a carrier. Two patients with hypocomplementemia (SLE and chronic nephritis) showed low serum opsonin activity, and phagocytic function of their granulocytes was enhanced. In cord blood and newborn infants serum opsonin activity was low, and phagocytic function of granulocytes was slightly decreased in cord blood but not in newborn infants. Patients with systemic bacterial infections showed an increased phagocytic function of granulocytes. Anti-cancer drugs decreased serum opsonin activity in children with leukemia or lymphoma. The children treated with L-asparaginase had very low opsonin activity, suggesting the drug inhibits complement synthesis. The measurement of whole blood CL was useful for monitering the phagocytic functions of blood after granulocyte transfusion.

Bacterial Infections↗
PubMed2000

Receptors involved in the phagocytosis of senescent and diamide-oxidized human RBCs.

BACKGROUND: Senescent RBCs bear IgG and C3 opsonins that are three to four times less than required for similar phagocytosis of experimentally opsonized RBCs. STUDY DESIGN AND METHODS: Studies were performed to determine the phagocyte receptors involved in phagocytosis in vitro. The effect of clustering of opsonins and oxidative damage in the sequestration of RBCs was studied by exposing RBCs to BS3 (bis[sulfosuccinimidyl]-suberate) and diamide (azodicarboxylic acid bis[dimethyl-amide]). RESULTS: Sequestration of senescent RBCs was inhibited by the treatment of lymphokine-activated monocytes with N-acetyl-D-galactoseamine (GalNAc), arginine-glycine-aspartic acid (RGD), or antibodies to CR3, FcgammaRI, FcgammaRII, leukocyte response integrin (LRI), and integrin-associated protein (IAP). Exposure to BS3 alone did not enhance phagocytosis. The addition of serum resulted in opsonin binding. The level of opsonization required for sequestration was higher than on senescent RBCs and was only marginally inhibited by blocking CR3, FcgammaRI and FcgammaRII. Diamide treatment alone did not lead to sequestration. Diamide-treated RBCs exposed to serum bound opsonin much as did senescent RBCs, and sequestration was inhibited by GalNAc, RGD, and antibodies to CR3, FcgammaRI, FcgammaRII, LRI, and IAP. CONCLUSION: Membrane alterations resulting in the binding of opsonins and the sequestration of senescent RBCs may be similar to those that occur on diamide-oxidized RBCs. They suggest the need for cooperative events among oxidation, clustering and cross-linking, and serum opsonization.

Complement C3↗
PubMed1994

Local serum application: restoration of sufficient host defense in human peritonitis.

Intra-abdominal host defense in human peritonitis is hampered by a severe dysfunction of phagocytosis due to an almost complete breakdown of bacteria opsonization. This defect relates to some opsonin consumption, but mainly to proteolytic and oxidative opsonin destruction. To restore and protect intact opsonins we have developed a clinical approach of intra-operative peritoneal serum application. In a prospective, controlled, and randomized study of 30 patients with generalized peritonitis we have investigated the impact of this adjuvant therapy on biochemical parameters and clinical features. Serum application induced a rise in opsonin concentration and, even more pronounced, opsonin function (P < 0.01) of several hours' duration, leading to a distinct improvement of bacteria elimination. In addition, alpha 1-proteinase inhibitor (alpha 1-P)I levels were significantly increased after 1 h (P < 0.05) in the treatment group. The follow-up by APACHE II scoring indicated an improvement in the therapy group over the whole observation period of 14 days. Lethality in the therapy group was 33% compared to 53% in controls. These results indicate that the intra-operative restoration of physiologic intra-abdominal milieu can improve bacteria opsonization and elimination, thus contributing to a favourable clinical course in abdominal sepsis.

Adult↗
PubMed1985

Impairment of opsonic function in children with hematologic malignancy during remission induction therapy.

The activity of complement-mediated opsonin was measured by the whole blood chemiluminescence method in 17 children with hematologic malignancy (including 6 with ALL, 7 with ANLL and 4 with non-Hodgkin's lymphoma) during remission induction therapy. The activity of opsonin, which was at the normal level before chemotherapy, decreased in all of the children during the therapy. This phenomenon was especially marked in the children treated with L-asparaginase. Although no clear relationship was found between the decrease in opsonin activity and the susceptibility to infection, it was confirmed that in 4 children having an episode of sepsis or septic fever, the infection started when the granulocyte decreased to the nadir, and simultaneously the activity of opsonin decreased. Therefore, it may be reasonable to suspect the decrease in opsonin activity when treating children with such infections.

Adolescent↗
PubMed1995

Liposome clearance from blood: different animal species have different mechanisms.

The kinetics of blood clearance and the mechanisms of liposome uptake by the reticuloendothelial system (RES) were compared in two animal species (mice and rats). By employing an in situ liver perfusion technique with selected liposome compositions (PC/Chol, PC/Cho/PS, PC/Chol/GM1 and PC/Chol/PEG5000-PE), we demonstrated that liposomes with same lipid composition exhibited different blood circulation half-lives in different animal species. Although liver is the major organ responsible for the clearance of liposomes from blood in both animal species, the specific mechanisms differ. In mice, liposome uptake by the liver did not involve specific serum opsonins. In contrast, liposome uptake by the rat liver was strongly dependent on serum opsonins. Further, the activity of serum opsonins for a given liposome composition differed among animal species. Human serum exhibited higher opsonin activities for PC/Chol and PC/Chol/GM1 liposomes than bovine sera, while rat serum displayed a high opsonizing activity for GM1 liposomes and none for liposomes composed of PC and Chol. The opsonin activity of human serum could be removed or decreased by treatment with EGTA/Mg2+, EDTA or cobra venom factor, suggesting that the activity is likely due to complement components. It is likely that C3 of the human complement system plays an important role in mediating the uptake of liposomes by the liver.

Animals↗