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Biomedical subjects

V Ghetie

Publications and source records attributed to V Ghetie.

At least 73 records · Page 4Linked to original sources
PubMed1986

Interaction between rabbit IgG immune complexes and Ricinus agglutinin.

Ricinus communis agglutinin covalently bound to Sepharose 4B (RcA-Sepharose 4B) was able to selectively bind immune complexes consisting of antigen (bovine serum albumin) and rabbit IgG antibody which were rich in antibody (i.e., high molecular weight complexes of approximately 2000 000). No interaction was recorded between RcA-Sepharose 4B and immune complexes consisting of the antigen plus rabbit IgG antibody which were rich in antigen (i.e., complexes with a molecular weight of 300 000-500 000). These results indicate that binding to RcA is due to the increased density of galactose residues in the high molecular weight polymeric antibody component of the soluble immune complexes.

Animals↗
PubMed1986

Protein A vectorized toxins--I. Preparation and properties of protein A-ricin toxin conjugates.

Protein A of Staphylococcus aureus (mol. wt 43,000) was covalently bound to ricin toxin (mol. wt 60,000) by N-succinimidyl 3-(2-pyridyldithio) propionate. The conjugate consisting of one molecule of protein A bound to one molecule of ricin toxin (mol. wt 100,000) was purified by successive affinity chromatographies on IgG-Sepharose 4B and ConA-Sepharose 4B. The purified protein A-ricin toxin conjugate was able to bind and kill IgG antibody coated leukemia EL4 cells leaving unaffected EL4 cells not coated with antibody. The cytotoxic efficacy of the conjugate was comparable to that of nonconjugated ricin toxin. The results recommend the use of protein A-ricin toxin conjugate as a "universal" specific toxin for the "in vitro" killing of various antibody-coated target cells.

Animals↗
PubMed1986

Interaction between human IgD and ricinus agglutinin.

The results show that monoclonal IgD reacts specifically with ricinus agglutinin (molecular weight 120,000) (RcAI). The reaction between IgD and RcAI was inhibited by galactose and lactose but not by glucose, indicating that the interaction is mediated by galactose containing carbohydrate units located in or near the sigma-hinge region. Affinity chromatography on RcAI-Sepharose 4B was successfully used to isolate monoclonal IgD from the IgD myeloma plasma.

Chromatography, Affinity↗
PubMed1985

Detection of human lymphocyte subpopulations by using monoclonal antibodies and protein A-coated erythrocytes.

The results obtained by using the protein A-rosette assay for human peripheral blood lymphocytes treated with a series of monoclonal antibodies were very close to the estimates obtained by indirect fluorescence. The percentages of T3-, T4-, T8- and DR-positive cells (T3 = T lymphocytes, T4 = helper T lymphocytes, T8 = suppressor T lymphocytes, DR = B, L and null cells) in normal and pathological peripheral blood were found to vary within the limits reported by many other authors using different techniques for the identification of cells binding the specific monoclonal antibody.

Animals↗
PubMed1984

Selective affinity of protein A containing staphylococci for monomeric and polymeric IgG.

Protein A containing staphylococci were saturated with human monomeric IgG (mIgG) and cross-linked with glutaraldehyde. The resulting material (SMG) preferentially bound aggregated IgG (aIgG) and soluble immune complexes (CIC). One milliliter of a 10% suspension of SMG bound approximately 30 micrograms of mIgG and 1000 micrograms of aIgG and CIC. The binding of aIgG to SMG was reduced to approximately 50% at a 20-fold excess of mIgG over aIgG. CIC and aIgG could be released from SMG by elution with 3 M KSCN. The results indicate that SMG can be used for identification and removal of CIC in patient plasma.

Antigen-Antibody Complex↗
PubMed1983

Isolation of a rabbit IgG fraction with cytophilic properties.

About 15% of rabbit IgG loaded on a column of Con A-Sepharose 4B was found to be specifically bound to the column due to a structural variation in its carbohydrate moiety. The Con A-retained rabbit IgG contained a higher amount of neutral hexoses than the initial IgG but its molecular weight, antigenic structure and half-life were identical or similar. The Con A-retained rabbit IgG has an affinity for the Fc receptor-bearing homologous macrophages which is 10 times higher than that of the initial IgG. The IgG fraction not retained on Con A-Sepharose is practically devoid of binding ability. These results suggest that the Con A-bound IgG may represent the cytophilic fraction of monomeric IgG responsible for the binding of IgG to Fc receptor-bearing cells.

Animals↗
PubMed1982

Receptors for IgA on human thymus cells in myasthenia gravis.

Specific surface receptors for the Fc region of human immunoglobulin A (Fc alpha R) were identified on the thymus cells of all 15 patients affected by myasthenia gravis. A large variation of the percentage of Fc alpha R bearing thymus cells was recorded (9 . 5-66 . 0%; mean value 27 . 9 +/- 17 . 8) the high values being associated in most cases with the thymus hyperplasia and the low values with a lipomatosis of the organ. Even the lowest percentage of Fc alpha R bearing cells recorded in myasthenia gravis are considerably higher than those found in normal subjects (0 . 4-4 . 1; mean value 1 . 8) demonstrating that the expression of Fc alpha R on the thymus cells is the consequence of the disease. No attempts were made to identify the cell population bearing Fc alpha R but indirect results indicate that the cells belong to E-rosette forming population, and, in some cases, to a null cell population devoid of the ability to form E and EAC rosettes, Fc alpha R can bind various IgA ligands and the binding is confined to a small fraction of IgA (not more than 5%) considered as cytophilic IgA.

Absorption↗
PubMed1981

Simultaneous detection of two different cell surface antigens by electron microscopy by means of multivalent hybrid antibody with double specificity.

Multivalent hybrid antibody (MHA) complexes with dual specificity were prepared by combining two antibodies of different specificities, one against ferritin (Fer), the other against horseradish peroxidase (HRP), with protein A of Staphylococcus aureus (SpA). Electron microscopy of mouse spleen lymphocytes and thymocytes (previously coated with mouse IgG anti-Thy-1 antibody) treated with IgG anti-Fer/SpA/IgG anti-mouse Ig complex and Fer gave better resolution and higher accuracy than previously obtained with IgG anti-HRP/SpA/IgG anti-mouse Ig complex and HRP (Mandache et al., 1980). Surface Thy-1 alloantigen and Fc receptor (charged with human IgG) treated with a mixture of IgG anti-Fer/SpA/IgG anti-Thy-1 and IgG anti-HRP/SpA/IgG anti-human Fab could be simultaneously detected on the thymocyte surface by either light or electron microscopy using Fer and HRP. The concomitant visualization of Thy-1 alloantigen (with Fer) and FcR (with HRP) on mouse thymocyte clearly shows that their distribution is largely independent and that the amount of Thy-1 antigen is greater. These results show that electron microscopy with a mixture of MHA is a useful technique for simultaneous location of two antigenic markers on the cell surface.

Animals↗
PubMed1981

An immunological hypothesis for plasma protein catabolism.

A selective mechanism of plasma protein catabolism is suggested, based on three main assumptions: (1) plasma proteins are submitted to molecular ageing thus achieving "modified" forms after a given time period; (2) the system recognizing the "modified" molecules consists of preformed physiological autoantibodies; (3) the elimination of the immune complexes formed between "modified" proteins and the corresponding autoantibodies takes place via binding to Fc receptor bearing cells.

Animals↗
PubMed1980

Staphylococcus aureus and protein A as mitogens for rabbit T lymphocytes.

The thymidine uptake by rabbit lymph nodes, spleen and peripheral blood lymphocytes was stimulated by Protein A (SpA) and SpA-containing staphylococci. The cell fraction enriched in T lymphocytes showed a higher degree of stimulation with SpA than the fraction enriched in B cells. Rabbit thymocytes showed a marked thymidine uptake by treatment with SpA but not with staphylococci. The monovalent fragment B of SpA (reacting with IgG) neither stimulated nor inhibited the incorporation of thymidine in rabbit lymph node lymphocytes indicating that the Fc reacting site of SpA cannot be responsible for the mitogenicity.

Animals↗
PubMed1979

Binding of cytophilic rabbit IgG to homologous hepatocytes.

Rabbit liver cells were able to bind cytophilic monomeric and polymeric homologous IgG via their Fc receptor binding sites (FcR). On the other hand, non-cytophilic rabbit IgG did not bind to hepatocytes, even after its aggregation. The present findings suggest that FcR on rabbit liver cells are specific for cytophilic monomeric IgG but do not significantly bind non-cytophilic, polymeric IgG.

Animals↗
PubMed1979

Effect of protein A of Staphylococcus aureus on the binding of monomeric and polymeric IgG to Fc receptor-bearing cells.

The effect of protein A of Staphylococcus aureus (SpA) on the binding of rabbit IgG to the Fc receptors of mouse lymphocytes and macrophages was found to correlate with the aggregation of the IgG ligands. After binding anti-erythrocyte IgG complexed with SpA, the cells were able to attach to and kill erythrocyte indicator cells with a higher efficiency than lymphoid cells treated with anti-erythrocyte IgG alone. The amount of anti-peroxidase IgG which can be bound to effector cells was not changed by reaction with SpA. In contrast, the binding to cells of IgG-coated erythrocytes and of anti-peroxidase IgG complexed with peroxidase was substantially reduced by reaction with SpA. The results are compatible with the presence of two distinct Fc receptors, one for cytophilic monomeric IgG and another for polymeric (antigen-complexed) IgG.

Animals↗
PubMed1978

I. An ultrastructural investigation on erythrocytes and lymphocytes coated with proteins: use of CrCl3 as an electron-dense marker.

Proteins (human immunoglobulin G and protein A of Staphylococcus aureus) coupled to the surface of erythrocytes (sheep, mice, man and chicken) and to mouse spleen lymphocytes by chromic chloride technique acquire electron-dense properties and may be visualized in electron microscopy. Sheep red blood cells coated with rabbit anti-erythrocyte antibodies and treated with chromic chloride showed continuous electron-opaque labelling of the cell membrane due to chelation of rabbit IgG with chromium atoms.

Animals↗
PubMed1978

Separation of cells by affinity chromatography on SpA-sepharose 6MB.

A cell separation technique was designed which was based on the reaction of protein A of Staphylococcus aureus (SpA) with the Fc regions of IgG antibodies. SpA covalently linked to Sepharose 6MB is able to fix antibody-bearing cells, while non-fixed cells are removed by washing. The fixed cells can be released by dog IgG or by mechanical treatment. As an example of the use of the technique, Ig-bearing cells were isolated from mouse spleen cells treated with rabbit IgG anti-mouse Ig antibody; the purity of the Ig-bearing lymphocytes so isolated was better than 90%. The viability and the ability of the cells to shed the antibodies from their surface were not significantly impaired by the fractionation method. The technique can be generally applied to cell separation providing IgG antibodies against specific surface markers are available.

Animals↗
PubMed1978

Effect of cell density on the disappearance of cell surface immunoglobulins.

Mouse macrophages and human peripheral blood lymphocytes exhibiting on the membrane autologous IgG as well as mouse thymocytes coated with human IgG, showed a strong cell concentration dependence of surface IgG disappearance during an incubation at 37 degrees C. Mouse spleen lymphocytes treated with anti-mouse Ig behaved in the same way regarding the disappearance of surface immunoglobulins, while the redistribution of ligands (cap formation) was not dependent on cell concentration.

Animals↗