PubMed Health⌕ Search

Biomedical subjects

Y Aida

Publications and source records attributed to Y Aida.

At least 145 records · Page 8Linked to original sources
PubMed1985

Topographical analysis of tumor-associated antigens on bovine leukemia virus-induced bovine lymphosarcoma.

Tumor-associated antigens (TAAs) expressed on tumor cells from cattle with enzootic bovine leukosis were divided into three groups by using 13 monoclonal antibodies: common TAA; partially common TAA; and individually distinct TAA. TAA was extracted from tumor cells and purified by ion exchange chromatography on diethylaminoethyl-cellulose and isoelectric focusing. The common TAA, which was detected on all tumors tested, was eluted with 0.6 M KCl in ion exchange chromatography on diethylaminoethyl-cellulose, and the isoelectric point of the antigen was 6.8. The partially common TAA, which was detected on some (but not all) of the tumors tested, was eluted with 0.4 to 0.8 M KCl, and the isoelectric points of the antigen were 5.3, 5.8, and 6.4. The individually distinct TAA was present in the fractions eluted with 0.4 to 0.8 M KCl, and the isoelectric point of the antigen was 5.5. Results of competitive binding assay and Western blot analysis showed that the common TAA was a polypeptide with a molecular weight of 74,000; that it has at least two independent antigenic regions; that the partially common and individually distinct TAAs were a polypeptide with a molecular weight of 64,000; and that the antigenic determinants on the common TAA, partially common TAA, and individually distinct TAA existed independently from each other.

Animals↗
PubMed1985

Tumor-associated antigens on bovine leukemia virus-induced bovine lymphosarcoma identified by monoclonal antibodies.

Thirteen monoclonal antibodies directed against tumor cells from cattle from enzootic bovine leukosis (EBL) were obtained. They reacted with tumor cells but not with normal bovine cells or bovine leukemia virus antigens. According to the reactivities of these antibodies with 19 individual tumors, the 13 monoclonal antibodies can be divided into three groups. Antibodies of the first group reacted with all the EBLs tested; those of the second group reacted with several, but not all, of the EBLs tested; and those of the third group reacted only with homologous tumor cells. Therefore, tumor-associated antigen (TAA) on the EBL tumor may possess common TAA, partially common TAA, and individually distinct TAA. The TAAs were solubilized from the tumor cells by treatment with 0.2% sodium deoxycholate and partially purified by diethylaminoethyl-cellulose column chromatography. Eleven of the 13 monoclonal antibodies reacted with this soluble TAA. The monoclonal antibodies belonging to the first group inhibited in vitro the growth of the bovine lymphoid cell line derived from the EBL tumor.

Adsorption↗
PubMed1985

Down-regulation of Fc receptor expression in guinea pig peritoneal exudate macrophages by muramyl dipeptide or lipopolysaccharide.

Expression of Fc receptors on the plasma membrane of guinea pig peritoneal exudate macrophages (PEM) was suppressed to almost one-half of that of the controls by long-term exposure to lipopolysaccharide (LPS) or muramyl dipeptide (MDP) in culture. The effect of the reagents was dose and time dependent, and as little as 0.5 ng/ml LPS or 5 ng/ml MDP was effective for the suppression. The expression of the Fc receptors decreased to 60 to 70% of the control level at 48 hr and to 45 to 50% at 72 hr after incubation of the cells in the presence of LPS or MDP. A Scatchard plot of the binding of 125I-soluble immune complexes (I.C.) to the cells revealed that the decrease in the binding of 125I-I.C. is due to a reduction in the number of Fc receptors on the cell membrane and not to a decreased affinity of the receptors. The membrane protein was radio-labeled with 125I, and the Fc receptors were purified by being bound to insoluble I.C. The specific binding of the 125I-labeled Fc receptors, from the LPS-treated macrophages, to the insoluble I.C. was almost one-half of that from the untreated control cells. SDS-PAGE analysis of the purified 125I-labeled Fc receptors revealed that the major peak of the m.w. 44,000 molecule in the LPS-treated cells was almost one-half of that of the control. Contrary to the effect of LPS or MDP, 72-hr incubation of macrophages with MIF-rich supernatant, cultured from lymph node cells, enhanced the expression of Fc receptors. Macrophages were treated with I.C. for 4 hr at 37 degrees C to remove the Fc receptors from the surface membrane. The reappearance of the receptors on the plasma membrane of the cells was significantly suppressed by LPS and MDP. The effect of LPS on the binding of five murine monoclonal antibodies (Ab) raised against PEM to the macrophage membrane and also that of 125I-wheat germ agglutinin (WGA) or 125I-insulin was studied. The monoclonal Ab were selected for their activity to induce superoxide anion generation in the macrophages, as do I.C., although the binding sites for the monoclonal Ab were not related to Fc receptors. The bindings of the five monoclonal Ab were not affected by exposure of the cells to LPS or MDP. Macrophages treated with the reagents bound as much 125I-insulin or WGA as did the untreated control cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1985

Characterization of three monoclonal antibodies which induce and modulate superoxide anion generation in guinea pig macrophages.

Three monoclonal antibodies (Ab), termed KY 12, KY 22, and KY 25 and raised against guinea pig macrophages, induced superoxide anion (O2-) generation in the cells. Although each monoclonal Ab bound to macrophages, each had a different pattern of binding to other cell types. In response to each of the Ab, the amount of O2- generated by 5 X 10(5) macrophages was between 0.5 and 0.7 nmol/min and was augmented threefold to fivefold by the addition of F(ab')2 fragments of rabbit Abs to mouse Ig. When macrophages were pretreated with soluble immune complexes (I.C.) prior to stimulation by the monoclonal Ab, the O2- generation stimulated by KY 12 or KY 22 was reduced by more than 70%. In contrast, pretreatment of macrophages with I.C. did not reduce O2- generation in response to KY 25. KY 12 and KY 22 stimulated adenyl cyclase activity in macrophages, but KY 25 did not. Pretreatment of the cells with soluble I.C. did not interfere with the enhancing effect of the monoclonal Ab on adenyl cyclase activity. Pretreatment of macrophages with KY 12 reduced by over 60% of subsequent generation of O2- in response to wheat germ agglutinin, I.C., formyl-methionyl-leucyl-phenylalanine, phorbol myristate acetate, KY 22, or KY 25. KY 22 or KY 25 did not suppress the generation of O2- in response to other stimuli. These results suggest that KY 22 and KY 25 activate O2- generation in a manner that differs from that of KY 12. These monoclonal Ab should prove useful in examining the regulation of O2- production.

Adenylyl Cyclases↗
PubMed1985

Fc receptor-mediated desensitization of superoxide (O2-) generation response of guinea-pig macrophages and polymorphonuclear leucocytes.

Guinea-pig macrophages were pretreated with soluble immune complexes (1 hr, at 37 degrees). By this procedure, the capacity of the cells to produce superoxide anions (O2-) upon stimulation with wheatgerm agglutinin (WGA) was inhibited by as much as 80% (desensitization). However, the receptors for WGA were still available on the cell surfaces as determined by the binding of 125I-labelled WGA to both the pretreated and control cells. This inhibition of O2- generation was also observed when opsonized zymosan (Op-zymosan) was used as the stimulus for O2- generation. In contrast, the inhibition by soluble immune complexes was less than 25% of the control levels when the desensitized cells were stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP) or phorbol myristate acetate (PMA). The same procedure was also used to desensitize guinea-pig polymorphonuclear leucocytes (PMN). In this case, the O2- generation of the PMN was suppressed to 50-55% of the control level when WGA or fMLP was used as stimulus. However, the PMA-induced O2- generation was far less affected by this treatment, as was the case with the macrophages. The activity of the desensitized macrophages for O2- generation recovered gradually to a normal level 24 hr after removal of the immune complexes from the medium. These results suggest that (i) some regulatory mechanisms which suppress the activation of NADPH oxidase are accentuated by prolonged exposure of guinea-pig macrophages and PMN with soluble immune complexes; (ii) the mechanism for O2- generation mediated by WGA or Op-zymosan may be different from that for O2- generation mediated by PMA, and (iii) the mechanism for O2- generation mediated by fMLP differs between macrophages and PMN.

Animals↗
PubMed1985

Usefulness of monoclonal antibodies for detection of enzootic bovine leukemia cells.

Monoclonal antibodies against tumor-associated antigens (TAAs) expressed in the leukemic cells of enzootic bovine leukosis (EBL) were examined for their possible usefulness in detecting EBL tumor cells. The antibodies immunohistochemically reacted with EBL tumor cells and had cytotoxic activity against the cells but not against normal adult bovine peripheral blood lymphocytes (PBL) even after activation with mitogens. The TAA-positive EBL tumor cells also had B cell surface markers. The TAA was also found in several samples of PBL taken from BLV-infected healthy cattle (8 positive out of 81 tested), as well as in PBL from 13 out of 14 cattle with lymphocytosis but no evidence of tumor. Thus, monoclonal antibodies directed against TAAs might be a useful tool not only for diagnosing EBL but also for screening of BLV-infected cattle with the potential to develop tumors in the future.

Animals↗
PubMed1984

Structural studies of Fc receptors. III. Isolation and molecular weight analysis of the component chain of Fc gamma receptor of macrophage.

Surface receptors of guinea pig peritoneal macrophages specific for the Fc region of IgG (Fc gamma receptor) were isolated and identified as a surface-radioiodinated component with a molecular weight of 44,000 that bound in an Fc-specific manner to IgG2 of guinea pig immunoglobulin immobilized in any of the following three different ways: IgG2 antibody in insoluble immune complex, IgG2 antibody bound to antigen-coupled Sepharose, and IgG2 covalently coupled to Sepharose. In order to obtain the Fc gamma receptor retaining the binding activity, the Fc-binding component was isolated by IgG2 affinity chromatography in which mild acidic buffer (pH 5.0-4.0) was chosen to elute the component bound to the affinity column. Forty-five to sixty-two percent of the eluted radioactivity was shown to rebind to the IgG2-affinity column. The bound fraction showed a single radioactive peak of 44,000 daltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The Fc-binding component isolated by the affinity chromatography behaved similarly in gel filtration in the presence of a detergent, as did the detergent-solubilized Fc gamma receptor before isolation by affinity chromatography. These results suggested that the Fc gamma receptor was isolated in a native form. Furthermore, it was confirmed that the isolated Fc gamma receptor is distinct from actin or the actin-like protein (DNase I-binding protein) which had been reported to bind to IgG-affinity column.

Animals↗
PubMed1984

Triggering of the superoxide generation of macrophages by crosslinking of Fc gamma receptor.

Crosslinking of monomeric IgG2 molecules bound to the Fc gamma receptors on the cell surface of guinea pig macrophages generated the triggering signal for the superoxide-generating system. A binding experiment indicated that macrophages have saturable binding sites for monomeric IgG2. Scatchard analysis of the binding data showed that macrophages have an average of 4 X 10(5) binding sites per cell and the association constant for the binding was 4.2 X 10(6) M-1. Binding of monomeric IgG2 to macrophages could be detected by subsequent reaction with the 125I-labeled F(ab')2 fragment of rabbit antibody specific for guinea pig Fab. Although binding of IgG2 monomer to Fc receptor did not stimulate superoxide release, further addition of the F(ab')2 fragment of anti-guinea pig Fab antibody did induce generation and release of superoxide, and the amount released was dependent on the dose of cell-bound IgG2. When macrophages were bound with a constant dose of IgG2 monomer in the first step, the superoxide release triggered by the addition of the F(ab')2 of anti-guinea pig Fab was dependent on the dose of the F(ab')2 fragment added. These results show that crosslinking of Fc receptors triggers the superoxide generation.

Animals↗
PubMed1984

Structural studies of Fc receptors. IV. Structure required for phospholipids for reconstitution of the delipidated Fc receptor of macrophages.

To analyze the interaction of the macrophage Fc receptor with phospholipids, we established an experimental system for delipidation of Fc receptor fraction and reconstitution of the Fc receptor activity in phospholipid vesicles. The separation of FcR from membrane phospholipids was achieved by ion exchange chromatography on DEAE-cellulose of the anionic detergent-lysate of the crude membrane fraction of guinea pig macrophages in the presence of detergent. The separation was based on the difference in charge between the complex of FcR and the anionic detergent and that of phospholipids and the detergent. The FcR fraction free of phospholipids showed no FcR activity as assessed in terms of its ability to inhibit the binding of labeled soluble immune complex of IgG2 antibody to macrophages, but the same fraction showed a definite activity when associated with phospholipids. This fraction was shown to contain a component of 44,000 daltons that is susceptible to surface-labeling and binds to IgG2-Sepharose in the affinity chromatography, indicating this component to be the Fc receptor. Reconstitution experiments with this fraction showed that phosphatidylcholine is the most effective phospholipid to reconstitute the FcR activity among those tested. Phosphatidylserine, phosphatidylinositol, and sphingomyelin were ineffective, while phosphatidylethanolamine showed a moderate effect. The inactivating effect of phospholipase C treatment on the Fc receptor activity of the membrane was shown to be due to the cleavage of phospholipids in the membrane but not due to modification of the Fc receptor molecule itself.

Animals↗
PubMed1984

Structural studies of Fc receptors. V. Effect of phospholipase C treatment on the binding activities of the Fc receptor of macrophage or its isolated plasma membrane.

The effect of phospholipase C treatment on the binding activity of the Fc receptor of guinea pig macrophage was studied to analyze the interaction of the Fc receptor with membrane phospholipids necessary for the activity. It was confirmed by subcellular fractionation that the receptor is localized on the plasma membrane. Treatment of the whole cell or isolated plasma membrane with phospholipase C of Clostridium perfringens diminished the binding of soluble IgG2-immune complex to Fc receptors on the cell or membrane. On the other hand, phospholipase C of Bacillus cereus did not affect the activity when it acted on the whole cell but it did diminish the activity when it acted on the isolated plasma membrane. Analysis of the phospholipids of untreated and treated macrophages or plasma membrane showed that phosphatidylcholine molecules, particularly those located in the membrane (not accessible to attack from the cell surface by phospholipase C of B. cereus), appear to be crucial for efficient interaction of macrophage Fc receptors with immune complex. Ligand-binding experiments with macrophages showed that the diminished binding activity was due to a decrease of the avidity for immune complex, but did not seem to be due to a decrease in the number or affinity of Fc receptors for monomeric IgG2. Taken together with the previous results which demonstrated that Fc receptors which had apparently lost the activity due to delipidation could be reconstituted with phosphatidylcholine but not with most other phospholipids, the results seem to indicate that the diminution of the binding activity to the immune complex of macrophage or its plasma membrane caused by phospholipase C treatment is due to the impairment of multivalent interaction between Fc receptor molecules on the membrane and IgG2 molecules in the immune complex, probably as a result of the loss of interaction of the head groups of phospholipids with Fc receptor molecules and the change in membrane properties resulting from the increase of diglycerides.

Animals↗
PubMed1983

Structural studies of fc receptors. II. The effect of dissociation and reassociation of phospholipids on the activity of Fc gamma receptors of macrophages.

The receptor for the Fc portion of immunoglobulin G (Fc receptor) of guinea pig macrophages was solubilized with a detergent and partially delipidated to the point where the ligand binding activity was essentially lost. Delipidation of the Fc receptor was done by fractionating the macrophage lysate by gel filtration in the presence of detergent. The elution behavior of Fc receptor-detergent complex and phospholipid-detergent mixed micelles varied depending on the kind of detergents used for membrane solubilization and for gel filtration. Separation of phospholipids from Fc receptor was best achieved when octylglucoside-solubilized fraction was chromatographed on Sepharose CL-6B in the presence of deoxycholate; the phospholipid peak emerged at Kav = 0.55 and the Fc receptor at Kav = 0.45. The fraction of Kav = 0.45 showed only a marginal activity when the activity was measured after removal of detergents, but activity was clearly shown when phospholipid fraction was added to this fraction prior to removal of the detergents. Reappearance of the Fc receptor activity was shown to be due to association of phospholipids with the Fc receptor. Three kinds of phospholipids with different polar head groups examined, phosphatidylcholine, phosphatidylserine, and phosphatidylethanolamine, were all able to reconstitute active Fc receptor, although phosphatidylethanolamine was somewhat less effective than the others. Thus, our study demonstrated the amphipathic nature of the Fc receptor, the binding of which is dependent on the interaction with phospholipids.

Animals↗