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S Avrameas

Publications and source records attributed to S Avrameas.

At least 127 records · Page 7Linked to original sources
PubMed1983

Thirty-six human monoclonal immunoglobulins with antibody activity against cytoskeleton proteins, thyroglobulin, and native DNA: immunologic studies and clinical correlations.

Six hundred and twelve monoclonal Ig (MIg) were studied for their antibody activity against the following autoantigens: actin, tubulin, thyroglobulin, myosin, myoglobin, fetuin, albumin, transferrin, and double-stranded DNA (dsDNA). Of these 612 MIg, 36 (i.e., 5.75%) were shown to possess antibody activity. Thirty-two of these 36 (5.22% of the total) were mainly directed against actin. The four others were directed, respectively, against tubulin, myosin, thyroglobulin, and dsDNA. The interaction of the MIg with the respective antigen was demonstrated by immunoenzymatic methods with monospecific antisera and by blotting experiments. Furthermore, this interaction in the 12 cases studied was mediated by the dimeric fragment F(ab')2 of the MIg. The MIg with antitubulin, antithyroglobulin, and anti-dsDNA activities were exclusively inhibited by their homologous antigens. Those with antiactin activity were predominantly inhibited by actin and also by tubulin and thyroglobulin. The one binding to myosin was, for the most part, inhibited by myosin and also significantly by actin and tubulin. Retrospective clinical analysis was possible for 31/36 patients. Twenty-six of 31 had malignant lymphoplasmocytic disorders. The five others were followed for miscellaneous disorders without overt signs of multiple myeloma (MM) or Waldenström's macroglobulinemia (WM). The correlation between the antibody activity of the MIg and the clinical features is discussed. These results indicate that a high proportion of MIg possess antibody activity against actin (5.22%). This incidence contrasts sharply with the positive reactions found toward all the other antigens tested: only one each for dsDNA, tubulin, thyroglobulin, and myosin, and none against myoglobin, fetuin, albumin, and transferrin. The significance of these results and the relationship between MIg and natural antibodies are discussed.

Actins↗
PubMed1983

Murine hybridomas secreting natural monoclonal antibodies reacting with self antigens.

Spleen cells from nonimmunized BALB/c mice were fused with two nonsecreting myeloma lines. The hybrids were selected in HAT medium and screened for Ig production and for antibody activity against actin, tubulin, myosin, thyroglobulin, myoglobin, spectrin, dsDNA, fetuin, and transferrin. Among 161 hybrids secreting Ig, three were found to react with DNA, one with thyroglobulin, and one mainly with myosin. Two of these hybrids could be propagated and further characterized. On the basis of inhibition experiments, one was found to be directed against dsDNA; the other was directed mainly against myosin but at the same time reacted significantly with actin, tubulin, spectrin, and dsDNA. Reactivity with myosin seemed to be concentrated in the light meromyosin subfragment, known to be rich in alpha-helical structure. These results indicate: 1) There are reactive B cell clones directed against self antigens. 2) The antibody specificities found for these antibodies are very similar to those found for natural antibodies in normal human serum and for human monoclonal Ig. 3) The widespread reactivity found for the clone mainly reacting with myosin raises the possibility that the determinant recognized by this antibody is a conformational structure that possibly is associated with alpha-helical structures.

Actins↗
PubMed1982

Miniaturization of beta-galactosidase immunoassays using chromogenic and fluorogenic substrates.

Enzyme immunoassay techniques are widely use to quantify various antigens and antibodies. The final step of these techniques (i.e. enzyme reaction) may be carried out in several ways (e.g. chromogenic, fluorogenic, or radioactive substrate and thermometric measurement). This paper compares the effectiveness of the chromogenic and the fluorogenic substrates in the beta-galactosidase immunoassay. Using microtitration plates (150 microliter samples) coated with anti-human IgE, and anti-human IgE labeled with E. coli beta-galactosidase, the lowest concentrations of IgE that one could detect employing either the chromogenic (o-nitrophenyl-beta-D-galactopyranoside) or the fluorogenic (4-methyl-umbelliferyl-beta-D-galactopyranoside) substrate were determined. It was found that both substrates were almost equally effective in measuring the lowest concentration of IgE (0.075-0.13 IU/ml) under the optimal conditions. But, using fluorogenic substrate and suitable apparatuses the enzyme immunoassay can be miniaturized. Thus by using decreasing volumes of reagents, progressively smaller amounts of antigen were quantified: as the sample volumes were reduced from 150 to 10 microliter and finally to 0.3 microliter a progressive decrease from 7 x 107 molecules of IgE to 2.9 x 107 molecules and to 1.5 x 106 molecules was observed. The corresponding lowest detection limits were 0.075 IU/ml, 0.46 IU/ml and 0.8 IU/ml.

Animals↗
PubMed1981

TerELISA: the ELISA test performed in Terasaki plates.

The use of Terasaki (10 microliter samples) and microtitration (100 microliter samples) plates as the solid phase in enzyme immunoassays was compared. Various antigens were used for coating the plates and antibodies present in human sera were evaluated using the same anti-human Ig antibody labelled with either beta -galactosidase, alkaline phosphatase, peroxidase or glucose oxidase. The results obtained, either by scoring with the naked eye or by absorbance reading with appropriate densitometers, showed that both plates were equally suitable and that the 4 enzymes were equally effective in detecting the same lowest quantity of antibody. A comparative evaluation using either Terasaki or microtitration plates for the quantitation of human anti-Echinococcus granulosus antibody ii 50 sera demonstrated that there was a good correlation between the two procedures (r = 0.8097). Finally, the use of glucose oxidase as the enzyme marked allowed a clear-cut distinction to be made between positive and negative samples with the naked eye alone.

Antigen-Antibody Reactions↗
PubMed1981

Cross-linking of surface immunoglobulins and endocytosis of antigen are not sufficient to suppress antibody production of two hybridoma cell lines.

The two cell lines Lev 1-3 and AS3, which secrete monoclonal anti-levan antibody and express surface membrane immunoglobulins that are capable of binding the levan, were cultured for 24 h or 48 h with levan of various molecular weights (5 x 10(4), 2 x 10(5) or 2 x 10(7) daltons). The production of antibody was measured by a plaque-forming cell assay for AS3 cells and by biosynthetic labelling for Lev 1-3 cells. Surface immunoglobulins were detected by a rosette-forming cell assay. By using immunoenzymatic procedures, we observed that levan of 5 x 10(4) and 2 x 10(5) daltons was intensely endocytosed by the cells and localized mainly in the cellular center, whereas levan of 2 x 10(7) daltons remained mostly associated with the plasma membrane and formed surface aggregates. After transfer of cells in levan-free medium, it was shown that internalized levan could persist several days inside the cells without being degraded. Viability, growth, antibody synthesis and secretion were not modified in cells cultured with levan, whatever the molecular weight of the antigen used. Our results show that cross-linking of surface immunoglobulins by multivalent antigen or endocytosis of antigen do not appear to be sufficient to induce a suppression of antibody production or membrane immunoglobulin expression.

Animals↗
PubMed1980

Lectin immuno tests: quantitation and titration of antigens and antibodies using lectin-antibody conjugates.

We have investigated the possibility of using lectin-antibody conjugates as general reagents in immunological procedures requiring a labeled antigen or antibody. Using these conjugates, labeling is achieved through saccharide binding sites of lectins which operate as acceptors for glycoconjugate marker substances added secondarily. Marker substances used in this work were enzymes, radioactively labeled glycoconjugates and erythrocytes, but other markers can also be used. Using the first two markers, antigens and antibodies were determined with accuracy and sensitivity equal to those of conventional enzyme or radioimmunoassays. Using erythrocytes as a marker, a simple erythro-adsorption procedure, possibly followed by hemolysis, has been developed which allowed the titration of antigens and antibodies to be carried out with a sensitivity at least equal to enzyme or radioimmunoassays.

Animals↗
PubMed1980

Direct evaluation of class-specific anti-DNA antibodies by an immunoenzymatic technique.

Antibodies against native DNA have been evaluated by an immuno-enzymo assay (ELISA) using glucose oxidase labelled Ig class-specific antibodies. Results of the ELISA test were significantly correlated with those of the Farr test performed with native DNA as well as with the degree of clinical activity. ELISA is proposed as a simple method for the direct evaluation of class-specific anti-native DNA antibodies in systemic lupus and related diseases.

Antibodies, Antinuclear↗
PubMed1980

A morphological and functional study on antigen binding and endocytosis by immunocytes.

Immunoenzymatic techniques were used to study antigen binding and endocytosis by lymph node cells of rats immunized against horseradish peroxidase, hen ovalbumin and rabbit IgG. The number of antigen-binding cells varied and depended on the type of antigen used, the time after immunization, and was higher after a booster injection. In secondary responses (4 days after booster), about 80% of antigen-binding cells were proplasmocytes and plasmocytes; by a double staining procedure it was found that 82% of these cells bore in addition to surface antigen, specific intracytoplasmic antibody as well. About 20% of antigen-binding cells were small and medium lymphocytes which did not contain detectable intracytoplasmic antibody. For ultrastructural studies of the endocytosis, peroxidase was used as the antigen. This antigen was found in cytoplasmic compartments which consisted of vesicles, cisternae and large round bodies (lysosomes?) often located near the Golgi apparatus. However, the cisternae of the Golgi apparatus, involved in the synthesis of specific antibody were not sites of retrieval of endocytosed antigen. The effect of endocytosis of antigen on the secretion and synthesis of antibody was studied by the local haemolysis plaque assay and biosynthetic labelling. No change was detected in antibody secretion and synthesis as a result of antigen endocytosis.

Animals↗
PubMed1980

In vivo and in vitro effects of colchicine and vinblastine on the secretory process of antibody-producing cells.

The sensitivity of the secretory process of antibody-synthesizing cells to microtubule-binding drugs, colchicine and vinblastine sulfate, was studied. Rats were immunized by footpad injections of horseradish peroxidase, and the popliteal lymph nodes were removed at various times after injection. Both in vivo effects of colchicine and in vitro effects of colchicine and vinblastine were studied. Quantitative data were obtained with in vitro drug-treated cells by labeling with L-3H-leucine and by measuring the secreted and the cytoplasmic immunoglobulins. It was found that inhibition of immunoglobulin secretion was about 78% and 93% by colchicine and vinblastine, respectively. the results obtained with the latter drug were more difficult to interpret because it also inhibited the biosynthesis of total proteins, and particularly that of immunoglobulins. Immunocytochemical studies of the in vivo and in vitro drug-treated cells performed by light and electron microscopy showed that in antibody-containing cells the Golgi area was often occupied by dilated antibody-containing vesicles, probably derived from the Golgi apparatus. In a few of these cells it was observed that antibody-containing rough endoplasmic reticulum was markedly dilated. the above results demonstrate that both microtubule-binding agents, colchicine and vinblastine, are potent inhibitors of the secretory process of plasma cells and seem to indicate that a correlation may exist between ultrastructural changes and inhibition of secretion.

Animals↗
PubMed1979

Skin fibroblast microtubular network in Alzheimer disease.

A preliminary observation from another laboratory recently suggested that a systemic microtubular defect may exist in Alzheimer disease. To investigate this hypothesis, we obtained skin biopsies from 4 patients with Alzheimer disease and 2 age-matched controls. Fibroblast cultures were established and the tubulin networks examined using immunoadsorbent purified antitubulin antibody and the indirect immunoperoxidase technique as well as electron microscopy. The cells were also examined after treatment with vinblastine and at senescence. The microtubular network appeared as delicate fibers radiating from the perinuclear region toward the cytoplasmic margins. No differences were recognized between the controls and the fibroblast cultures from patients with Alzheimer disease. Microtubules were not visualized following incubation with vinblastine, but positively staining intracytoplasmic paracrystalline inclusions were noted. No abnormalities of microtubules were recognized in the electron microscopic examinations. These findings suggest that the neurofibrillary neuronal degeneration of Alzheimer disease is not a manifestation of a systemic disorder of the microtubular network.

Alzheimer Disease↗