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D R Schultz

Publications and source records attributed to D R Schultz.

At least 19 recordsLinked to original sources
PubMed1995

Antibody-independent binding of complement component C1q by Legionella pneumophila.

Incubation of Legionella pneumophila Philadelphia 1 in normal human serum depleted of either classical-pathway component C1q or alternative-pathway component factor B resulted in activation of the complement system. Experiments focused on the role of the classical pathway in complement activation revealed that legionellae bound C1q independently of antibody. Purified preparations of L. pneumophila major outer membrane protein but not serogroup 1 lipopolysaccharide bound C1q independently of antibody. This suggests that antibody-independent binding of C1q by L. pneumophila can result in activation of the classical pathway in normal human serum and that major outer membrane protein may be a C1q acceptor on the L. pneumophila cell surface.

Antibodies, Bacterial↗
PubMed1994

Brevetoxin PbTx-2 immunology: differential epitope recognition by antibodies from two goats.

The epitopic regions of the brevetoxin PbTx-3 molecule, produced by the marine dinoflagellate Ptychodiscus brevis, have been identified by structural modification at three distinct regions of the toxin. These are: the A-ring lactone region of the molecule, the K-ring side-chain and the H-ring. The modified PbTx-3 derivatives were tested for their ability to bind brevetoxin goat antisera directed against the PbTx-3 molecule, by radioimmunoassay. The results showed that at least two major epitopes and one minor epitope are recognized: the A-ring lactone region of the molecule and the K-ring side-chain, and the H-ring. The results illustrate the variety of antibodies which may be produced, even within a species, and suggests that epitope characterization is important in the development of assays which are to be employed in seafood safety issues.

Animals↗
PubMed1992

Functional properties of heterogeneous human asialo-C4 and its isotypes C4A and C4B.

The fourth component of human complement (C4) is encoded at two separate but closely linked loci within the MHC on the short arm of chromosome 6. Thus, there are two types of C4 protein in most individual and pooled normal human sera (NHS): C4A and C4B. Incubation of individual sera, pooled NHS, or purified heterogeneous C4 (C4A/C4B) with bacterial sialidase at 37 degrees C increased C-mediated hemolysis of antibody-sensitized sheep erythrocytes 1.54- to 1.93-fold. Comparative studies of Tmax of human C2, using asialo-C4 or buffer-treated C4 on EAC1gp and extrapolation to time 0 indicated a z value 4-fold higher with asialo-C4. This indicated that more hemolytically active C42 complexes are available with sialidase-treated C4 compared to untreated C4. There was no appreciable difference in the % 125I-C4 bound to EAC1gp (sialidase- or buffer-treated). Sera from two different blood donors with C4A3 phenotype (C4BQ0), two different donors with C4B1 phenotype (C4AQ0), and serum from an individual heterozygous deficient at both C4A3 and C4B1 regions (A3, AQ0; B1, BQ0) were investigated. The C4 allotypes, purified from these sera, were treated with sialidase; the C4A3 was enhanced in hemolytic assays by sialidase-treatment (1.52- to 2.3-fold), whereas the C4B1 allotype was not enhanced. Fluorometric determinations revealed that approximately the same percentage of sialic acid was released from sialidase-treated C4A3 and C4B1. Therefore, the increase in hemolytic titer observed after treatment of NHS or purified heterogeneous C4 with sialidase is a property of C4A3 but not a property of C4B1.

Asialoglycoproteins↗
PubMed1992

Legionella pneumophila lipopolysaccharide activates the classical complement pathway.

Legionella pneumophila is a gram-negative bacterium capable of entering and growing in alveolar macrophages and monocytes. Complement and complement receptors are important in the uptake of L. pneumophila by human mononuclear phagocytes. The surface molecules of L. pneumophila that activate the complement system are unknown. To identify these factors, we investigated the effects of L. pneumophila lipopolysaccharide (LPS) on the classical and alternative complement pathways of normal human serum by functional hemolytic assays. Although incubation of LPS in normal human serum at 37 degrees C resulted in the activation of both pathways, complement activation proceeded primarily through the classical pathway. Activation of the classical pathway by LPS was dependent on natural antibodies of the immunoglobulin M class that were present in various quantities in sera from different normal individuals but were absent in an immunoglobulin-deficient serum obtained from an agammaglobulinemic patient. Additional studies using sheep erythrocytes coated with LPS suggested that the antibodies recognized antigenic sites in the carbohydrate portion of LPS. The ability of LPS to interact with the complement system suggests a role for LPS in the uptake of L. pneumophila by mononuclear phagocytes.

Complement C1↗
PubMed1990

Functional properties of the asialo-fifth component of human complement.

Removal of exposed, terminal sialic acid (SA) from carbohydrate chains N-glycosidically linked to asparagine residues of highly pure human C5 with bacterial sialidase increased C-mediated hemolysis of antibody-sensitized sheep E maximally 2.77-fold. Sialidase-treated C5 used as a reagent for the titration of C6, C7, C8, and C9 resulted in increased titers of all these components compared to buffer-treated C5. As determined by a fluorometric method, ca. 65% of the SA was enzymically hydrolyzed under optimal conditions. Endoglycosidase F incubated with C5 followed by monosaccharide analyses by anion exchange chromatography with pulsed amperometric detection revealed both high mannose and complex (terminate in SA) oligosaccharides were hydrolyzed; no effect was found on the functional activity of C5. Approximately 4% of the complex oligosaccharides were hydrolyzed from C5. Comparison of sialidase- and buffer-treated C5 decay rates from EAC1gp(4b,oxy2a,3b)hu resulted in two linear components of the decay curve with sialidase-treated C5, but one linear component with buffer-treated C5. Of the sialidase-treated 125I-C5 15% was bound to EAC1gp(4b,oxy2a,3b)hu compared to 9.3% of buffer-treated 125I-C5. Furthermore, 27% of sialidase-treated 125I-C5 was bound to EAC1gp,4bhu compared to 16.6% of buffer-treated 125I-C5, but no lysis occurred after the addition of C6-C9. The mechanism of increased hemolytic activity after removal of SA from C5 is: the Tmax is prolonged at 30 degrees C (ca. 15 min vs 9 min), and a higher percentage of C5 binds to cellular intermediates compared to buffer-treated C5.

Asialoglycoproteins↗
PubMed1990

Properties of four acute phase proteins: C-reactive protein, serum amyloid A protein, alpha 1-acid glycoprotein, and fibrinogen.

Four plasma proteins, referred to as positive acute phase proteins because of increases in concentration following inflammatory stimuli, are reviewed: C-reactive protein (CRP), serum amyloid A protein (SAA), alpha 1-acid glycoprotein (AAG), and fibrinogen. The CRP and SAA may increase in concentration as much as 1000-fold, the AAG and fibrinogen approximately twofold to fourfold. All are synthesized mainly in the liver, but each may be produced in a number of extrahepatic sites. The role of cytokines in induction of the acute phase proteins is discussed, particularly the multiple functional capabilities of interleukin-6 (IL-6). Other cytokines that regulate acute phase gene expression and protein synthesis include IL-1, tumor necrosis factor alpha, interferon gamma, as well as other stimulatory factors and cofactors. The physicochemical characteristics of each protein are reviewed together with the molecular biology. For each protein, the known biological effects are detailed. The following functions for CRP have been described: reaction with cell surface receptors resulting in opsonization, enhanced phagocytosis, and passive protection; activation of the classical complement pathway; scavenger for chromatin fragments; inhibition of growth and/or metastases of tumor cells; modulation of polymorphonuclear function; and a few additional diverse activities. The role of plasma SAA is described as a precursor of protein AA in secondary amyloidosis; other functions are speculative. AAG may play an immunoregulatory role as well as a role in binding a number of diverse drugs. In addition to clot formation, new data are described for binding of fibrinogen and fibrin to complement receptor type 3. Finally, the concentration of each protein is discussed in a wide variety of noninfectious and infectious disease states, particularly in connective tissue diseases. The quantification of the proteins during the course of various acute and chronic inflammatory disorders is useful in diagnosis, therapy, and in some cases, prognosis.

Acute-Phase Proteins↗
PubMed1989

Role of C1q in phagocytosis of Salmonella minnesota by pulmonary endothelial cells.

The Re mutant of Salmonella minnesota adheres in much greater numbers than the wild type to endothelial cells derived from the bovine pulmonary artery. Since the Re mutant is distinguished from wild-type S. minnesota by its ability to bind C1q and since endothelial cells possess receptors for C1q, we examined the role of C1q in the phagocytosis of the S. minnesota Re mutant. First, preincubating endothelial cells with C1q-enriched medium resulted in increased adherence of the Re mutant (17.9 x 10(4) versus 6.6 x 10(4]. Second, preincubating the Re mutant with C1q-enriched medium resulted in increased numbers of adherent bacteria (62.1 x 10(4) versus 6.6 x 10(4]. Preincubation of both endothelial cells and bacteria with C1q-enriched medium resulted in increased adherence above control levels but less adherence than when either cells or bacteria were preincubated separately in C1q-enriched medium. If serum depleted of C1q was used for preincubation of endothelial cells or bacteria, adherence was reduced below control levels. Thus, C1q plays an important role in the initial steps (recognition, binding, and ingestion) of phagocytosis. Next, the role of C1q was investigated in the respiratory burst response. Levels of superoxide anion released from endothelial cells 15 min after phagocytosis of the Re mutant (100 bacteria per endothelial cell) were assayed by measurement of the superoxide dismutase-inhibitable reduction of ferricytochrome c. Superoxide anion release was increased during phagocytosis of the Re mutant (35 nmol of O2- per 3 x 10(6) endothelial cells) and was also elevated above control values by incubation with soluble C1q (10 nmol of O2- per 3 x 10(6) endothelial cells). These results indicate a role for C1q in both the ingestion and the response of endothelial cells to the S. minnesota Re mutant.

Animals↗
PubMed1989

Measurement of complement proteins C2 and B in systemic lupus erythematosus and septic shock.

We developed sensitive radioassays to quantitate the homologous complement proteins C2 and B, in intact form, in sera from patients with diseases associated with hypocomplementemia. In a study of systemic lupus erythematosus (SLE) patients, we found a subset of patients (6/40) with low C2 concentrations, though overall, C2 concentration was not related to disease activity. Protein B concentration was increased in 23/40 SLE patients, apparently not due to a generalized acute phase response. Among patients with both gram-negative and gram-positive septic shock, C2 and B concentrations were low in a subset of patients with pre-existing cirrhosis, suggesting hepatic hyposynthesis of these proteins may be important in their prognosis and predisposition to severe infections.

Biomarkers↗
PubMed1989

Erythrocyte membrane protein deficiencies in paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder characterized by intermittent hemolytic anemia. Membrane abnormalities of blood cells from patients with PNH are the reason for the unusual sensitivity to lysis by autologous plasma complement. A patient with typical clinical disease consistent with PNH is described together with a few strategies and pitfalls for treatment. Commonly used in vitro assays are discussed that document the complement-mediated lysis of aberrant PNH erythrocytes. Membrane-associated proteins that are abnormal in PNH cells, the characteristics of these proteins, and their mechanism(s) of action are described; these include the decay accelerating factor that inhibits the C3/C5 convertases of both complement pathways on cell surfaces, the C8 binding protein that modulates a step in terminal complement lysis, and other proteins that regulate complement-mediated lysis at early or late steps of the complement cascade.

Adult↗
PubMed1988

The second component of human complement: detection of two hemolytic forms in plasma by pH variation.

The second component of human complement (C2) in pseudoglobulin prepared from normal plasma eluted as a single peak at high conductivity (30 mS) and pH 4.5 from the cationic exchangers S-Sepharose or Mono S in the Fast Protein Liquid Chromatography (FPLC) System. The C2 was stable at pH 4.5 and 0 degrees C if enzyme inhibitors were used and the pH was raised to 6.0 after elution from the columns. After rechromatography on Mono S in the FPLC System at the median isoelectric point of 5.5 or pH 6.0, the C2 eluted as two distinct hemolytic forms: the first peaked at 16 mS, the second at 30 mS. The two forms of C2 did not correlate with the allotypic variant of C2 in individual, normal human plasmas. After elution at pH 4.5 from S-Sepharose and rechromatography at pH 5.5 or 6.0 on Mono S, the hemolytic activities of the two forms in individual plasmas eluted in 3 patterns: 1) high activity at 16 mS, low activity at 30 mS; 2) low activity at 16 mS, high activity at 30 mS; 3) high activity at 16 mS, high activity at 30 mS. The specific activities of both forms were approximately the same; both eluted the same after gel filtration at pH 5.5, and both had the same pattern on SDS-PAGE and immunoblots. The pattern of elution was characteristic for each individual plasma, and the first hemolytic form appeared to elute independent of the second form. At pH 4.5, C2 was completely separated from Factor B, a functionally and structurally similar protein of the alternative complement pathway, whereas at pH 5.5 or 6.0, the two proteins eluted together. From these results, the two forms of hemolytic C2 can be purified for structural and functional analyses.

Chromatography, Ion Exchange↗
PubMed1988

The second component of human complement: use of glycosidases and glucosylation to distinguish the two forms.

The two forms of human plasma C2 that were described in the preceding report (1) were investigated for their functional and biochemical differences. Incubation with the neuraminidase (NAN'dase) of Clostridium perfringens at 37 degrees C resulted in a four- to fivefold increase in the hemolytic activity of both forms. The increase in activity was different than the increase caused by treatment with iodine. The mechanism of increased activity of NAN'dase-treated C2 was the generation of increased molecules of activated C3 (C3b), resulting in more molecules of C5 binding to (C4b, 2a, 3b)n. Removal of N-acetyl-neuraminate from C2 did not alter its binding to a cationic exchanger. Nonenzymatic glucosylation was used to distinguish the two forms of C2. Incubation of highly pure C2 with 14C-D-glucose resulted in the gradual accumulation of radioactivity in acid-precipitable material. The two forms of C2 were glucosylated in vitro for seven days with 14C-D-glucose in phosphate-buffered saline at 25 degrees C. Form 2 bound twice as much 14C-D-glucose as form 1. Glucosylated form 2, but not form 1, lost some of its affinity to bind to a cationic exchanger. Since the interaction between glucose and protein occurs at free amino groups, we conclude that form 2 of C2 has approximately twice as many free amino groups as form 1. This explains the reason for the existence of two forms of C2 in plasma independent of the allelic variant.

Complement C2↗
PubMed1986

Receptor-mediated binding of C1q on pulmonary endothelial cells.

Normal undamaged pulmonary endothelial cells appear to be immunologically privileged in that they do not express receptors for the Fc portion of IgG nor for C3b. However, these receptors become unmasked on endothelial cells injured by viral infection or exposure to white cell lysates. We now present evidence to indicate that C1q binds to specific receptors on the surface of normal healthy endothelial cells. The binding is dose-dependent, reversible and saturable. Furthermore our data show that binding of C1q to endothelial cells is via the collagenous portion of the molecule not via the globular head regions. Thus binding of C1q to endothelium would have the effect of exposing Fc receptors that could then bind to IgG of circulating immune complexes. That Fc receptors are in fact exposed is shown by rosette formation with antibody sensitized erythrocytes. With 2C1r-2C1s-associated C1q, no binding occurred using C1 fixation and transfer assays. Our results indicate that C1q binding to endothelium provides a means for localizing immune complexes on pulmonary vessels and may be important in the initiation and progression of the inflammatory response.

Animals↗
PubMed1986

Complement activation in septic shock patients.

To evaluate the status of the complement system and to determine the effects of corticosteroids on complement component levels in septic shock, C3, C4, and Factor B were measured in 42 patients with severe late septic shock. Serum levels of C4 and Factor B correlated with C3 levels (r = 0.48 and 0.64, respectively; p less than .01) in patients in shock for more than 4 h, but only Factor B correlated with C3 (r = 0.85; p less than .01) in patients in shock for 4 h or less. C3 and Factor B levels were significantly (p less than .05) lower in patients who died (12,174 +/- 1,524 CH50 U/ml and 14 +/- 1 mg/dl, respectively) than in patients who survived (18,418 +/- 2,833 CH50 U/ml and 21 +/- 2 mg/dl, respectively). Corticosteroids did not alter complement component levels. The alternative pathway appears to be activated early in septic shock, whereas the classical pathway is activated later. C3 and Factor B levels may predict survival of patients in septic shock. In this study, corticosteroids did not change the complement component levels of patients in late severe septic shock.

Complement Activation↗
PubMed1986

Elevated levels of immunoglobulins and immune complexes in the bile of patients with primary sclerosing cholangitis.

The concentration of immunoglobulins and immune complexes was determined in the serum and bile of four patients with primary sclerosing cholangitis, only one of whom had chronic ulcerative colitis, and in four postcholecystectomy control patients. The result of the immunoglobulin studies demonstrated increased serum levels of IgM in primary sclerosing cholangitis as compared to control patients. The IgG, IgA, and IgM in bile were all significantly elevated as compared to controls (p = 0.02). Immune complexes in bile and serum were also determined in both groups by the C1q and conglutinin binding assays. Immune complexes in bile were elevated in three of four of the patients with primary sclerosing cholangitis. These findings further characterize primary sclerosing cholangitis in terms of biliary immunoglobulins and immune complexes but do not resolve whether these changes are an epiphenomenon or reflect a primary role of immunoglobulins and immune complexes in the pathogenesis of this disorder.

Adult↗
PubMed1984

The effects of a partially purified fraction of an ant venom in rheumatoid arthritis.

A partially purified extract of an ant venom from the South American tree ant Pseudomyrmex sp. was tested in a double-blind, controlled study of patients with rheumatoid arthritis. Venom treated patients demonstrated an improvement in global efficacy and a decrease in the number of tender/painful joints and swollen joints. Swollen joint index improved in 60% of venom treated patients. Other parameters did not demonstrate significant change. Reduction of joint swelling was followed by symptomatic improvement that was sometimes delayed by weeks. Reactions were limited to erythema at the injection site (all patients), local pruritus (two-thirds of the patients), and fever with malaise (one-third of the patients). Further study of this venom in rheumatoid arthritis appears warranted in view of its apparent favorable efficacy-to-toxicity ratio.

Adult↗