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Biomedical subjects

Y Masuho

Publications and source records attributed to Y Masuho.

105 records · Page 6Linked to original sources
PubMed1984

Interaction of monoclonal antibodies with cell surface antigens of human ovarian carcinomas.

Two monoclonal antibodies, OC 125 and OC 133, bind to distinct determinants on the surface of human epithelial ovarian carcinoma cell lines. OC 125 and OC 133 recognize determinants on molecules with molecular weights greater than 200,000 and 80,000, respectively. When binding to four different cell lines was compared, apparent affinity constants for OC 125 ranged from 3.1 X 10(9) to 6.0 X 10(7) M-1, whereas those for OC 133 ranged from 1.6 X 10(9) to 8.5 X 10(8) M-1. An estimate of the number of antigenic determinants per cell ranged from 1.0 X 10(7) to 2.8 X 10(5) for OC 125 and from 4.0 X 10(5) to 3.4 X 10(4) for OC 133. Antigenic determinants recognized by OC 125 and OC 133 could be detected in spent culture medium. When radiolabeled OC 125 was incubated with each of four ovarian tumor cell lines, approximately 90% of the antibody remained bound to the tumor cell surfaces for more than 20 hr. Similar binding of OC 133 was observed with three of the four ovarian tumor cell lines. By contrast, greater than 70% of OC 133 antibody was either shed or endocytosed after binding to OVCA 433 cells over the same period. Antigenic modulation was not induced by either antibody interacting with any of the four cell lines. These data suggest that antigen may be lost from the surface of human ovarian carcinoma cells by several different mechanisms and that antigen release is not inconsistent with binding of radiolabeled antibody to the tumor cell surface for prolonged periods.

Antibodies, Monoclonal↗
PubMed1984

Selective elimination of a B cell subset having acceptor site(s) for T cell-replacing factor (TRF) with biotinylated antibody to the acceptor site(s) and avidin-ricin A-chain conjugate.

A covalent conjugate of avidin with ricin subunit A-chain (avidin-RA) was prepared by using N-succinimidyl 3-(2-pyridyldithio)propionate as a coupling agent. Selective cytotoxic activity after the combined treatment of spleen cells with biotinylated antibody and avidin-RA was demonstrated by the fact that the responsiveness to LPS was selectively abrogated by pretreatment of the cells with biotinylated rabbit anti-mouse immunoglobulin (MIg) antibody, but not with biotinylated anti-Thy-1.2 antibody. Neither the biotinylated antibody alone nor avidin-RA alone was effective in decreasing the responses to mitogens. Moreover, a high anti-DNP PFC response elicited by DNP-KLH-primed BALB/c mouse spleen cells stimulated in vitro with DNP-KLH was mostly abrogated by the pretreatment of the cells with biotinylated anti-MIg antibody and avidin-RA. Again, neither the biotinylated antibody alone nor avidin-RA alone was effective in decreasing the anti-DNP PFC response. This cell-killing method with the use of biotinylated antibody and avidin-RA was applied and evaluated in experimental systems in which the helper action of T cells on B cells was mediated by T cell-replacing factor (TRF) or was performed by the direct interaction of T cells with B cells (cognate interaction). When DNP-KLH-primed splenic B cells, pretreated with biotinylated F(ab')2 fragment of DCF1 male anti-BALB/c-B IgG antibody against acceptor site(s) for TRF followed by treatment with avidin-RA, were stimulated with DNP-OVA in the presence of monoclonal TRF, the anti-DNP PFC response was significantly decreased, whereas the same treated B cells responded well to stimulation with DNP-PPD in the presence of Tbc-primed T cells (cognate interaction). These results indicate that B cells responsible for the cognate interaction and those having TRF acceptor site(s) belong to a distinct subpopulation of B cells, and that the cytocidal action of the noncovalent conjugate of the antibody and RA formed from the biotinylated antibody and avidin-RA via an avidin-biotin complex has immunologic selectivity, eliminating only the latter subset of B cells recognized by the antibody.

Animals↗
PubMed1983

Ricin A-chain conjugated with monoclonal anti-L1210 antibody. In vitro and in vivo antitumor activity.

In studies of antitumor antibody-cytotoxic agent conjugates as potential antitumor agents with improved tumor specificity, the toxic subunit A-chain of ricin was conjugated with a monoclonal antibody to a tumor-associated antigen expressed weakly on murine leukemia L1210 cells and strongly on L1210/GZL cells, a guanazole-resistant subline of L1210, employing N-succinimidyl 3-(2-pyridyldithio)propionate as cross-linking agent. The conjugate (anti-L1210 conjugate) exhibited a potent concentration-dependent cytotoxicity against cultured L1210/GZL cells, and inhibited cell growth at concentrations over 0.8 micrograms/ml. The conjugate killed all L1210/GZL cells at a concentration of 100 micrograms/ml. Neither nonimmune conjugate similarly prepared from mouse nonimmune IgG nor unconjugated anti-L1210 IgG alone showed cytotoxicity against L1210/GZL cells. When (BALB/c X DBA/2)F1 mice inoculated with 1 X 10(5) L1210/GZL cells were treated with IP injections of 27 micrograms anti-L1210 conjugate 1 h and 5 days after tumor cell inoculation, a life-prolonging effect was observed. [Lifespan in treated animals as percentage of that in controls (T/C) = 146%]. However, when the dose per injection was increased to 50 micrograms per mouse, survival was the same as in the control group. Postmortem examination of mice that had been treated with 50 micrograms anti-L1210 conjugate revealed lesions with necrosis and hemorrhage in the liver parenchyma and the intestinal epithelium, respectively. A similar toxic effect on the host mice was also observed with nonimmune conjugate.

Animals↗
PubMed1983

Selective inhibition of anti-nucleoside-specific antibody production by nucleoside-ricin A conjugate.

The effect of the preincubation of peripheral blood lymphocytes, from SLE patients, with nucleoside-ricin A conjugates on spontaneous A,G,C,T antibody production was examined. Enhanced spontaneous anti-nucleoside-specific antibody (anti-A,G,C,T antibody) production by SLE B cells was selectively inhibited by pretreatment in vitro with nucleosides conjugated to the ricin A chain. The selective suppression was demonstrated by the lack of suppression of the anti-DNP response or of polyclonal IgG production by pretreatment that did suppress anti-A,G,C,T production by the lymphocytes of eight patients with SLE. Furthermore, pretreatment of B cells, but not of T cells, with nucleoside-ricin A conjugates inhibited the A,G,C,T antibody response by these B cells. Thus, (A,G,C,T)-BGG-ricin A conjugates bind directly to the nucleoside-specific B cells via their antigen receptors. This demonstration of the selective elimination of B cells might have therapeutic applications in SLE.

Antibodies, Antinuclear↗
PubMed1982

Importance of the antigen-binding valency and the nature of the cross-linking bond in ricin A-chain conjugates with antibody.

As a continuation of our work on toxin A-chain conjugates with antitumor antibodies for selective delivery of the toxin to the target cells, four ricin A-chain conjugates were prepared by linking A-chain to Fab' or F(ab')2 of rabbit IgG against L1210 with or without employing a cross-linking agent, N,N'-o-phenylenedimaleimide (PDM), N-succinimidyl 3-(2-pyridyldithio)propionate (SPDP) or N-succinimidyl m-(N-maleimido)benzoate (SMB), and the effects of antigen-binding valency and of the nature of the cross-linking bond on their in vitro cytotoxicity were studied. The relative potencies of the conjugates in terms of IC94's were as follows: F(ab')2-SPDP-A-chain, 100; Fab'-S-S-A-chain, 21; F(ab')2-SMB-A-chain, 1.3; Fab'-PDM-A-chain 0.38. Among the four conjugates, F(ab')2-SPDP-A-chain and Fab'-S-S-A-chain can be cleaved into the homing and the cytotoxic components with 2 mM 2-mercaptoethanol. These results suggest that divalency in antigen-binding and susceptibility of the cross-linking bond to cleavage by mercapto reagent are desirable for high potency. Protein synthesis in a cell-free system of rabbit reticulocyte lysate was inhibited by Fab'-S-S-A-chain and by Fab'-PDM-A-chain as effectively as by free A-chain, indicating that the liberation of A-chain is not important, at least on ribosomes, but it is important for the A-chain to reach a ribosome after binding of the conjugates to the cell-surface.

Animals↗
PubMed1980

Target-cell cytotoxicity of a hybrid of Fab' on immunoglobulin and A-chain of ricin.

As an approach to the development of new antitumor agents, a hybrid in which one molecule of the Fab' fragment of a rabbit anti-murine leukemia L1210 immunoglobulin G (IgG) was linked to the A-chain of ricin via a disulfide bone was prepared by the reaction of A-chain having one reactive thiol group with Fab' having one activated cysteine residue, followed by chromatography on Sephadex G-150 superfine. The hybrid exhibited a potent cytotoxicity towards L1210, whereas unconjugated Fab', unconjugated A-chain, or an equimolar mixture of the two showed no significant cytotoxicity. Furthermore, the hybrid with Fab' of normal IgG had no cytotoxicity towards L1210 cells. The results indicate that the hybrid manifests its toxic activity towards the target cells through binding of its Fab' moiety of cell surface antigens.

Animals↗
PubMed1979

Clinical effect and metabolism of S-sulfonated immunoglobulin in 7 patients with congenital humoral immunodeficiency.

7 patients with primary humoral immunodeficiency were given an S-sulfonated IgG preparation, 100 mg/kg i.v. at intervals of 3--4 weeks, for treatment of, or prophylaxis against, infection. The clinical effects and metabolism of S-sulfonated IgG were studied. No side reactions attributable to S-sulfonated IgG occurred in any of the patients. The S-sulfonated IgG was completely transformed into intact IgG within 24 h after administration, and had a mean half-life of 21 days, comparable to that of intact IgG. Complete restoration of IgG Fc fragment activity occurred within 24 h following injection, as assessed by reversed passive cutaneous anaphylaxis.

Animals↗
PubMed1977

Interaction of S-sulfonated human IgG with human complement and its components.

S-sulfonated human IgG (S-sIgG) was prepared by treating IgG with sodium sulfite and sodium tetrathionate. The treatment resulted in the selective cleavage of interchain disulfide bonds of the IgG to give S-sulfonate groups. Complement fixing activities of aggregated S-sIgG and the immune complex formed with the S-sIgG antibody were very weak. S-sIgG at a high dose reduced the activity of the first complement component (C1) in normal human serum without any reduction of other complement components activites, but S-alkylated IgG at the same dose did not. Loss of C1 activity was not caused by either S-sulfonated myeloma proteins (IgA and IgE) or urea-treated S-sIgG, in which both inter- and intra-chain disulfide bonds were cleaved. These results suggest that the selective reduction of C1 by S-sIgG is due to a conformational change of the immunoglobulin.

Complement Fixation Tests↗
PubMed1977

Development of an intravenous gamma-globulin with Fc activities. I. Preparation and characterization of S-sulfonated human gamma-globulin.

S-sulfonated gamma-globulin (S-GG) was prepared by treating gamma-globulin with sulfite and tetrathionate ions. About four interchain disulfide bonds were selectively cleaved to give S-sulfonate groups. Although the above treatment strongly suppresses anticomplementary activity and nonspecific skin reactivity, the resulting S-GG retains high antibody activity. Furthermore, S-GG was found to maintain satisfactory levels for prolonged periods in vivo. The physicochemical and antigenic analyses of S-GG suggest that the S-sulfonation induces structural modification only at restricted sites.

Complement Fixation Tests↗
PubMed1977

Development of an intravenous gamma-globulin with Fc activities. II. Reconversion of S-sulfonated human gamma-globulin into the original gamma-globulin.

The reconversion of S-sulfonated antitetanus gamma-globulin (S-GG) into the original gamma-globulin was studied. S-sulfonate groups in S-GG could be converted into disulfide bonds in vitro. The conversion restored the greater part of both complement-fixing and skin-sensitizing activities. S-GG administered intravenously formed interchain disulfide bonds again in vivo, which was accompanied by restoration of the C-dependent passive hemolytic activity. Intravenous injection of S-GG did not cause a significant decrease in serum complement level.

Biotransformation↗
PubMed1976

Reconstruction of intact gamma-globulin from S-sulfonated gamma-globulin in vivo.

The conversion of the S-surfonate group in a peptide to a disulfide bond has been observed in vitro. This paper reports that the conversion of this group in human S-sulfonated gamma-globulin (S-GG) appeared to occur in vivo judging from the change in molecular weight of S-GG observed in the presence of sodium dodecyl sulfate (SDS) and the restoration of hemolytic activity.

Animals↗