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M Soria

Publications and source records attributed to M Soria.

At least 37 records · Page 2Linked to original sources
PubMed1988

Activity of a monoclonal antibody-saporin-6 conjugate against B-lymphoma cells.

A monoclonal antibody reactive with the immunoglobulin heavy chain (TEC IgM) has been conjugated to saporin-6 (SAP), which is the major ribosome-inactivating protein from the seeds of the plant Saponaria officinalis. Studies with Burkitt's lymphoma cell line Bjab 113 demonstrate that this immunotoxin is capable of killing 3 logs (99.9%) of clonogenic lymphoma cells after a 2-hour incubation. The presence of human bone marrow inhibits the activity of the conjugate. However, full potency of TEC IgM-SAP immunotoxin is restored by adding 1 mM amantadine to the incubation medium. The reaction is highly specific and is inhibited by the presence of excess anti-mu-antibody or human serum. Clonal growth of other Burkitt's lymphoma cell lines is inhibited to a lesser extent by the immunotoxin. The presence of surface IgM on the different cell lines is directly correlated to target cell killing by TEC IgM-SAP. Isolation of Bjab 113 clones surviving treatment demonstrates that only a minority are truly resistant and that the others randomly escape the treatment. The highly potent and specific activity of this conjugate in the presence of bone marrow buffy coat and its exceptionally rapid onset of action make this conjugate a good candidate for the ex vivo elimination of neoplastic cells from the bone marrow of non-Hodgkin's lymphoma patients.

Antibodies, Monoclonal↗
PubMed1988

Synthesis and characterization of an antihuman T-lymphocyte saporin immunotoxin (OKT1-SAP) with in vivo stability into nonhuman primates.

The authors conjugated, by a disulphide bond, the antihuman T-lymphocyte (CD5) monoclonal antibody (MoAb) OKT1 to the saporin-6 (SAP) ribosome-inactivating protein of the plant Saponaria officinalis. The resulting OKT1-SAP immunotoxin bound to CD5-expressing target cells and under standard culture conditions specifically suppressed mitogen-induced-T-lymphocyte DNA and protein synthesis in a dose-related manner. T-lymphocyte killing was achieved by five-minute exposure of the target cells to OKT1-SAP. The concentration inhibiting 50% (IC50) of T-lymphocyte DNA synthesis was 0.32 nmol/L. The potency of OKT1-SAP was moderately enhanced by amantadine (IC50 0.08 nmol/L) but not by ammonium chloride or chloroquine. Whole blood components did not interfere with the efficacy of OKT1-SAP, as in vitro treatment of fresh whole blood resulted in effective elimination of clonable peripheral blood T-lymphocytes assessed by a limiting dilution assay. Because these characteristics of T-lymphocyte killing by OKT1-SAP (ie, rapidity of action, potency also without potentiators) and lack of inhibition by whole blood components may be relevant for the use of an immunotoxin as a therapeutic agent in humans, the authors evaluated the stability in vivo and the circulatory clearance of OKT1-SAP in cynomolgus monkeys. Following a single intravenous (IV) injection of nontoxic dosages (0.16 to 1.3 mg/kg), an initial rapid decline (t1/2 alpha = 1.0 to 4.1 hours) was followed by a long-lasting slower decrease (t1/2 beta = 11.6 to 20.6 hours) of OKT1-SAP plasma concentrations as detected by double-antibody solid phase enzyme-linked immunosorbent assay (ELISA) assay. Not only did OKT1-SAP remain intact immunologically but it also retained its biological activity, as measured by the ability of plasma samples from monkeys given immunotoxin to inhibit DNA synthesis in human T-lymphocytes. Taken together the findings presented in this article indicate the feasibility of using OKT1-SAP as a therapeutic tool and provide information that will facilitate the rational use of immunotoxins as a treatment modality in humans.

Animals↗
PubMed1987

Characterization of human ferritin H chain synthetized in Escherichia coli.

We have inserted the coding region of the cDNA for human ferritin H chain into the expression vector pEMBLex2. The plasmid obtained is able to direct the synthesis of the ferritin H chain in Escherichia coli up to a concentration of 15% of total soluble proteins. All expressed subunits are found correctly assembled in the complete ferritin molecule, which can be easily purified. We have shown that the ferritin synthesized in E. coli has an Mr, electrophoretic mobility, and thermal stability similar to natural human isoferritins and is recognized by monoclonal antibodies specific for the H, but not by those for the L human ferritin chains.

Cloning, Molecular↗
PubMed1986

Expression of the human apolipoprotein AI gene fused to the E. coli gene for beta-galactosidase.

The human apoAI gene was expressed in E. coli by in-frame fusion to a modified beta-galactosidase gene present in plasmid pUR291. The fused beta-galactosidase-apoAI gene product was expressed at a high level and was recognized by an anti-human apoAI antiserum. Besides the fused protein, at least one degradation product having an Mr similar to that of beta-galactosidase was present in high amounts in bacterial extracts. These results and those of a pulse-chase experiment indicate that degradation took place only in the apoAI moiety of the chimeric protein.

Apolipoprotein A-I↗
PubMed1985

Characterization of a Saponaria officinalis seed ribosome-inactivating protein: immunoreactivity and sequence homologies.

A ribosome inactivating protein from Saponaria officinalis, SO-6, was purified and the N-terminus sequenced. The sequence shows extensive homology with Pokeweed antiviral protein, Pokeweed antiviral protein II, Pokeweed antiviral seed protein and dodecandrin. SDS gel electrophoresis in the Laemmli system revealed two bands of similar intensities with a smear between them, probably an artifact due to the high pI of the protein. Use of a harsher denaturing gel system resulted in one band in electrophoresis. Immune antisera was raised in rabbits against this protein and it cross reacted with other proteins (SO-5, SO-8 and SO-9) from seeds of Saponaria officinalis, but not with gelonin, Momordica charantia inhibitor and dianthin 32.

Amino Acid Sequence↗
PubMed1985

Plasmid pFCE4: a new system of Escherichia coli expression-modification vectors.

Two versatile expression-modification vectors were obtained by inserting the origin of replication (ori) of phage f1 into the expression vector pOTS. The resulting plasmids produce large amounts of coding or noncoding ssDNA (depending on ori orientation in pFCE4+ and pFCE4-) and excrete it into the medium as virus-like particles following infection with phage f1. These features make them suitable for dideoxy chain termination sequencing, oligonucleotide directed mutagenesis and gene expression without further manipulations. The human IFN alpha-2 gene, lacking the codon for the first amino acid, cysteine, was efficiently expressed by these vectors.

Base Sequence↗
PubMed1984

Fibroblast interferon from a human amniotic cell line: a strategy for rapid molecular cloning.

A strategy for rapid cloning and identification of cDNA clones was employed to obtain fragments of the gene for human fibroblast (beta) interferon. A human amniotic cell line (UAC), widely used for interferon assay, yielded high titers of beta-interferon and was used as a source for cDNA synthesis. Recombinant clones were screened by a combination of hybridization conditions: (a) comparing clones that hybridized with radioactive cDNA from induced UAC cells vs cDNA from cells not induced for beta-IFN; (b) using a synthetic oligonucleotide proble complementary to a region of the beta-IFN gene. Among clones selected on the basis of their positive response to both screening procedure, one (4F7) was sequenced and shown to be highly homologous to the beta-IFN gene. This clone was used as a probe to screen a human chromosomal DNA library, yielding the entire chromosomal beta-IFN gene. A "Northern" hybridization analysis of UAC mRNA from uninduced and induced cells revealed the existence of a single molecular species of mRNA for beta-IFN with the expected molecular weight.

Amnion↗
PubMed1982

A human amniotic cell line yielding high titres of human fibroblast interferon.

A line of human amniotic cells (UAC) was found to yield large amounts of fibroblast interferon (IFN-beta; 100 to 150 IU/10(3) cells) upon induction with Newcastle disease virus (NDV). UAC cells have a doubling time of about 24 h, and do not require foetal calf serum for growth or optimal IFN yield. The IFN produced was shown to be HuIFN-beta by assaying it on homologous and heterologous cells, and by neutralization tests with specific antisera. It could be purified to a specific activity of 0 . 6 X 10(7) IU/mg protein by chromatography on Blue Sepharose. Addition of 8 micrograms poly(A+) RNA from NDV-induced UAC in 100 microliter of reticulocyte lysate resulted in the production of 510 +/- 340 IU/ml of an IFN that was neutralized only by anti-HuIFN-beta serum.

Amnion↗
PubMed1973

A cis-trans test of the effect of the first enzyme for histidine biosynthesis on regulation of the histidine operon.

Previous studies showed that when triazolalanine was added to a derepressed culture of a histidine auxotroph, repression of the histidine operon occurred as though histidine had been added (6). However, when triazolalanine was added to a derepressed culture of a strain with a mutation in the first gene of the histidine operon which rendered the first enzyme for histidine biosynthesis resistant to inhibition by histidine, repression did not occur. The studies reported here represent a cis/trans test of this effect of mutations to feedback resistance. Using specially constructed merodiploid strains, we were able to show that the wild-type allele is dominant to the mutant (feedback resistant) allele and that the effect operates in trans. We conclude that the enzyme encoded by the first gene of the histidine operon exerts its regulatory effect on the operon not by acting locally at its site of synthesis, but by acting as a freely diffusible protein.

Alanine↗