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Results for “OPSONINS”

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At least 181 records · Page 10Linked to original sources
PubMed1987

Haemophilus influenzae type b opsonins of intravenous immunoglobulins.

Immunoglobulin G may be prepared by different methods for intravenous infusion and administered as replacement therapy for hypogammaglobulinemia. Intravenous immunoglobulins prepared by different methods were compared in vitro for their ability to opsonize Haemophilus influenzae type b in the absence of complement and subsequently induce neutrophil chemiluminescence. While the antibody contents, measured by an enzyme-linked immunosorbent assay and radioimmunoassay, were equivalent, the immunoglobulin prepared by a non-molecular modifying method (ion-exchange chromatography) had the greatest ability to induce bacterial-neutrophil interaction, measured by chemiluminescence, while a reduced and alkylated immunoglobulin had the least. Thus, preparative methods may have a profound effect upon the function of intravenous immunoglobulins. The biological function of immunoglobulins for clinical use can be compared easily by neutrophil chemiluminescence.

Haemophilus influenzae↗
PubMed1995

An investigation on the role of plasma and serum opsonins on the internalization of biodegradable poly(D,L-lactic acid) nanoparticles by human monocytes.

We demonstrate here that polyethylene glycol (PEG) 6,000 protects biodegradable poly(D,L-lactic acid) nanoparticles (PLA NP) from extensive uptake by monocytes in plasma. These results are in agreement with those previously obtained with PEG 20,000 which reduced the uptake of PLA NP by human monocytes in phosphate buffered saline and plasma, and prolonged the NP circulation time in vivo. The coating efficiency of PEG 6,000 and 20,000 was substantially decreased in serum. The difference between the uptake of plain and coated NP clearly reappeared for PEG 20,000-coated NP in heat inactivated serum and in IgG-depleted serum. We suggest that typical plasma proteins, heat labile serum proteins (e.g. complement components) and IgG are involved in the opsonization of plain and coated PLA NP. Other proteins previously found to adsorb onto these NP, namely albumin and apolipoprotein E, did not appear to directly influence the uptake process.

Biodegradation, Environmental↗
PubMed1992

Purification and characterization of a humoral opsonin from the solitary urochordate Styela clava.

1. We have previously identified opsonic activity in the plasma of the solitary urochordate, Styela clava. 2. Here, we report the purification and further characterization of the opsonic molecule. 3. Two purification methods were employed. 4. Gel filtration yielded one strongly opsonic fraction that contained a single, electrophoretically-resolved protein. 5. Opsonic activity was dose-dependent and sensitive to tryptic digestion and heat denaturation. 6. SDS-PAGE and calibrated gel filtration indicated the opsonic protein was a 17.5 kDa monomer while isoelectrofocusing indicated a single pI of 7.0. 7. In an alternative procedure, a similar opsonic activity and protein were isolated by affinity purification using whole yeast cells.

Animals↗
PubMed1993

A novel role of Periplaneta lectin as an opsonin to recognize 2-keto-3-deoxy octonate residues of bacterial lipopolysaccharides.

1. Periplaneta lectin of the American cockroach was shown to have affinity to bacterial lipopolysaccharides (LPS) of chemotypes Rb-Re, but not to lipid A. 2. 2-Keto-3-deoxy octonate (KDO) was the most effective sugar so far tested for inhibition of the hemagglutinating activity of Periplaneta lectin. 3. Periplaneta lectin was suggested to participate in the clearance of bacteria injected into the abdominal cavity of the cockroach.

Animals↗
PubMed1988

Ingestion and killing of Streptococcus agalactiae by bovine granulocytes in the presence of natural opsonins.

An enzyme-linked immunosorbent assay (ELISA) demonstrated the presence of naturally acquired antibodies against Streptococcus agalactiae in normal bovine serum (NBS). In milk wheys, ELISA values were much lower than in sera. Pre-colostral calf serum (PCS) was shown to lack antibodies to type II and III S. agalactiae. The opsonic requirements of 10 human and 10 bovine strains were investigated by evaluating the phagocytosis-induced reduction of the incorporation of radiolabeled thymidine by streptococci. Antibodies present in NBS were required for the efficient ingestion of both human and bovine isolates type II by bovine granulocytes. Three out of five type III bovine isolates were opsonized in the absence of specific antibodies (opsonization by PCS) and type II and III bovine isolates did not require complement opsonization. By contrast, inactivation of complement reduced phagocytosis of human isolates and only one type III strain of human origin was opsonized by PCS. These findings suggest that human isolates had higher opsonic requirements. The phagocytic killing of 6 type III strains (5 mastitis isolates and the reference typing strain) was investigated. Opsonization by normal serum enabled bovine blood granulocytes to ingest and kill S. agalactiae. Nevertheless, greater than or equal to 35% of bacteria remained viable at the end of the phagocytosis incubation in 10% NBS. Heat treatment of serum decreased the efficacy of killing for only 3 of the 6 tested strains. An IgG2 fraction of normal adult bovine serum promoted active ingestion, which was still increased in the presence of PCS. Normal wheys displayed large variations in their ability to promote ingestion of S. agalactiae by blood granulocytes. The promoting effect was systematically less than that of serum from the same cow, and this can be related to the lower ELISA values found in wheys.

Animals↗
PubMed2005

Development of an opsonin inhibition assay for evaluation of complex polysaccharide protective epitopes.

The induction of opsonic antibodies directed against capsular polysaccharides (Ps) is an important mechanism by which immunization protects against the development of invasive pneumococcal (Pn) infection. In preparing Pn vaccines, it is necessary to compare different manufacturing lots of capsular Ps, or to compare oligosaccharides used for conjugate vaccines with native capsular Ps, in order to insure that important epitopes of the Ps are maintained. We have developed an opsonic-antibody inhibition assay (OIA) to compare the functional epitopes of different capsular Ps preparations in vitro. Components of the OIA are primary neutrophils, rabbit complement (C'), and type-specific antibody (Ab). After conditions for optimal opsonic killing were determined for each Pn serotype, anti-Pn Ab was pre-incubated with different dilutions of purified capsular Ps, then added to the OIA mix. Plotting the % bacteria killed versus Ps concentration (log transformed) yielded a linear curve that was used to quantify the concentration of capsular Ps which inhibited the bacteria killing by 50% (IC50). The IC50 was determined for 8 Pn Ps types. These ranged between 6 ng/ml for type 6B and 1268 ng/ml for type 23F. Importantly OIA curves were statistically identical for two different manufacturing lots of capsular Ps for the 8 Pn Ps types. We conclude that differences among capsular Ps used for Pn vaccines could be detected with an OIA assay and these differences may predict the ability of Ps preparations to induce functionally active antibody when formulated into vaccines.

Animals↗
PubMed1983

A human monocyte system for the assay of plasma opsonins.

Previous bioassays for studying the opsonic regulation of the monocyte-macrophage system are subject to a variety of serious disadvantages which limit their value. An assay system is described which avoids many of these pitfalls and is applicable to the rapid assay of large numbers of samples. Human monocytes were isolated from peripheral blood and Saccharomyces cerevisiae used as the target particle. Particle ingestion was assessed using an electronic particle size analyzer and a close correlation was shown between this assay and a visual assessment of ingested micro-organisms.

Biological Assay↗